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18 pages, 5521 KiB

Open AccessArticle

Green Synthesis of Fe–Cu Bimetallic Supported on Alginate-Limestone Nanocomposite for the Removal of Drugs from Contaminated Water

by Inas A. Ahmed, Hala. S. Hussein, Zeid A. ALOthman, Abdullah G. ALanazi, Norah Salem Alsaiari and Awais Khalid

Polymers 2023, 15(5), 1221; https://0-doi-org.brum.beds.ac.uk/10.3390/polym15051221 - 28 Feb 2023

Cited by 8 | Viewed by 1658

Abstract

In this study Fe–Cu supported on Alginate-limestone (Fe–Cu/Alg–LS) was prepared. The increase in surface area was the main motivation for the synthesis of ternary composites. Scanning electronic microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) were used to examine the [...] Read more.

In this study Fe–Cu supported on Alginate-limestone (Fe–Cu/Alg–LS) was prepared. The increase in surface area was the main motivation for the synthesis of ternary composites. Scanning electronic microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) were used to examine the surface morphology, particle size, percentage of crystallinity, and elemental content of the resultant composite. Fe–Cu/Alg–LS was used as an adsorbent for the removal of drugs such as ciprofloxacin (CIP) and levofloxacin (LEV)from contaminated medium. The adsorption parameters were computed using kinetic and isotherm models. The maximum removal efficiency of CIP (20 ppm) and LEV (10 ppm) was found to be 97.3% and 100%, respectively. The optimal conditions were pH 6 and 7 for CIP and LEV, optimum contact time 45, 40 min for CIP and LEV, and temperature of 303 K. The pseudo-second-order model, which confirmed the chemisorption properties of the process, was the most appropriate kinetic model among the ones used, and the Langmuir model, which was the most appropriate isotherm model. Moreover, the parameters of thermodynamics were also assessed. The results imply that the synthesized nanocomposites can be used to remove hazard materials from aqueous solutions. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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16 pages, 2622 KiB

Open AccessArticle

Study of Formulation and Process Variables for Optimization of Piroxicam Nanosuspension Using 3² Factorial Design to Improve Solubility and In Vitro Bioavailability

by Yahya Alhamhoom, Sandip M. Honmane, Umme Hani, Riyaz Ali M. Osmani, Geetha Kandasamy, Rajalakshimi Vasudevan, Sharanya Paramshetti, Ravindra R. Dudhal, Namrata K. Kengar and Manoj S. Charde

Polymers 2023, 15(3), 483; https://0-doi-org.brum.beds.ac.uk/10.3390/polym15030483 - 17 Jan 2023

Cited by 3 | Viewed by 1923

Abstract

Piroxicam is a Biopharmaceutical Classification System (BCS) Class II drug having poor aqueous solubility and a short half-life. The rationale behind the present research was to develop a Piroxicam nanosuspension to enhance the solubility and thereby the in vitro bioavailability of the drug. [...] Read more.

Piroxicam is a Biopharmaceutical Classification System (BCS) Class II drug having poor aqueous solubility and a short half-life. The rationale behind the present research was to develop a Piroxicam nanosuspension to enhance the solubility and thereby the in vitro bioavailability of the drug. Piroxicam nanosuspension (PRX NS) was prepared by an anti-solvent precipitation technique and optimized using a full-factorial design. Herein, the nanosuspension was prepared using polymer polyvinylpyrrolidone (PVP) K30^® and Poloxamer 188^® as a stabilizer to improve the solubility and in vitro bioavailability of the drug. Nine formulations were prepared based on 3² full-factorial experimental designs to study the effect of the formulation variables such as concentration of poloxamer 188 (%) (X₁) and stirring speed (rpm) (X₂) as a process variable on the response of particle size (nm) and solubility (µg/mL). The prepared NS was characterized by phase solubility, Fourier-transform infrared (FT-IR), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), particle size, zeta potential, entrapment efficiency, and percent drug release. DSC and XRPD analysis of freeze-dried NS formulation showed conversion of PRX into a less crystalline form. NS formulations showed a reduction in the size from 443 nm to 228 nm with −22.5 to −30.5 mV zeta potential and % drug entrapment of 89.76 ± 0.76. TEM analysis confirmed the size reduction at the nano level. The solubility was increased from 44 μg/mL to 87 μg/mL by altering the independent variables. The solubility of PRX NS in water was augmented by 14- to 15-fold (87.28 μg/mL) than pure PRX (6.6 μg/mL). The optimized formulation (NS9) at drug-to-stabilizer concentration exhibited a greater drug release of approximately 96.07% after 120 min as compared to the other NS formulations and pure PRX (36.78%). Thus, all these results revealed that the prepared NS formulations have improved the solubility and in vitro dissolution compared to the pure drug. Furthermore, an increase in the drug release was observed from the NS than that of the pure PRX. All these outcomes signified that the prepared PRX NS showed an increase in solubility and in vitro dissolution behavior; which subsequently would aid in attainment of enhanced bioavailability. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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18 pages, 2678 KiB

Open AccessArticle

Dosimetric Characterization of DSF/NaOH/IA-PAE/R. spp. Phantom Material for Radiation Therapy

by Damilola Oluwafemi Samson, Ahmad Shukri, Nurul Ab. Aziz Hashikin, Siti Hajar Zuber, Mohd Zahri Abdul Aziz, Rokiah Hashim, Mohd Fahmi Mohd Yusof, Nor Ain Rabaiee and Sylvester Jande Gemanam

Polymers 2023, 15(1), 244; https://0-doi-org.brum.beds.ac.uk/10.3390/polym15010244 - 03 Jan 2023

Viewed by 1600

Abstract

Background: Different compositions of DSF/NaOH/IA-PAE/R. spp. composite particleboard phantoms were constructed. Methods: Photon attenuation characteristics were ascertained using gamma rays from ¹³⁷Cs and ⁶⁰Co. Absorbed doses at the location of an ionization chamber and Gafchromic EBT3 radiochromic films were calculated [...] Read more.

Background: Different compositions of DSF/NaOH/IA-PAE/R. spp. composite particleboard phantoms were constructed. Methods: Photon attenuation characteristics were ascertained using gamma rays from ¹³⁷Cs and ⁶⁰Co. Absorbed doses at the location of an ionization chamber and Gafchromic EBT3 radiochromic films were calculated for high-energy photons (6 and 10 MV) and electrons (6, 9, 12, and 15 MeV). Results: The calculated TPR_20,10 values indicate that the percentage discrepancy for 6 and 10 MV was in the range of 0.29–0.72% and 0.26–0.65%. It was also found that the relative difference in the

d_{m a x}

to water and solid water phantoms was between 1.08–1.28% and 5.42–6.70%. The discrepancies in the determination of PDD curves with 6, 9, 12, and 15 MeV, and those of water and solid water phantoms, ranged from 2.40–4.84%. Comparable results were found using the EBT3 films with variations of 2.0–7.0% for 6 and 10 MV photons. Likewise, the discrepancies for 6, 9, 12, and 15 MeV electrons were within an acceptable range of 2.0–4.5%. Conclusions: On the basis of these findings, the DSF/NaOH/IA-PAE/R. spp. particleboard phantoms with 15 wt% IA-PAE addition level can be effectively used as alternative tissue-equivalent phantom material for radiation therapy applications. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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16 pages, 7073 KiB

Open AccessArticle

Synthesis and Characterization of Eco-Friendly Bio-Composite from Fenugreek as a Natural Resource

by Nayem Hossain, Mohammad Asaduzzaman Chowdhury, Tauhidul Islam Noman, Md. Masud Rana, Md. Hasan Ali, Raja Saad Alruwais, Md. Shafiul Alam, Khalid A. Alamry, Mahmood D. Aljabri and Mohammed M. Rahman

Polymers 2022, 14(23), 5141; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14235141 - 25 Nov 2022

Cited by 5 | Viewed by 1922

Abstract

The present study show the usability of starch (tamarind) based-bio-composite film reinforced by fenugreek by various percentages to replace the traditional petrochemical plastics. The prepared bio-composite films were systematically characterized using the universal testing machine (UTM), soil degradation, scanning electron microscope (SEM), X-ray [...] Read more.

The present study show the usability of starch (tamarind) based-bio-composite film reinforced by fenugreek by various percentages to replace the traditional petrochemical plastics. The prepared bio-composite films were systematically characterized using the universal testing machine (UTM), soil degradation, scanning electron microscope (SEM), X-ray diffraction (XRD), thermogravimetric analyzer (TGA), and antibacterial tests. The experiments showed that a lower percentage of fenugreek improves biodegradation and mechanical strength. More than 60% of biodegradation occurred in only 30 days. Almost 3 N/mm² tensile strength and 6.5% tensile strain were obtained. The presence of micropores confirmed by SEM images may accelerate the biodegradation process. Antibacterial activity was observed with two samples of synthesized bio-composite, due to photoactive compounds confirmed by FTIR spectra. The glass transition temperature was shown to be higher than the room temperature, with the help of thermal analysis. The prepared bio-composite containing 5% and 10% fenugreek showed antibacterial activities. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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15 pages, 2409 KiB

Open AccessArticle

Development of Polyphenol-Functionalized Gelatin-Poly(vinylpyrrolidone) IPN for Potential Biomedical Applications

by Lidia Escutia-Guadarrama, David Morales, Daniel Pérez-Calixto and Guillermina Burillo

Polymers 2022, 14(21), 4705; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14214705 - 03 Nov 2022

Cited by 3 | Viewed by 1933

Abstract

Owing to their suitable physical and chemical properties, hydrogels have been considered a convenient choice for wound dressings because of the advantages that they offer, such as maintaining the moist environment required for wound healing. In this research, interpenetrating hydrogels of polyphenol-functionalized gelatin [...] Read more.

Owing to their suitable physical and chemical properties, hydrogels have been considered a convenient choice for wound dressings because of the advantages that they offer, such as maintaining the moist environment required for wound healing. In this research, interpenetrating hydrogels of polyphenol-functionalized gelatin (GE), a water-soluble protein derived from natural polymer collagen with excellent biocompatibility, no immunogenicity, and hydrophilicity, and polyvinylpyrrolidone (PVP), a hydrophilic, non-toxic, biodegradable, biocompatible polymer that is soluble in many solvents, widely used in biomedical applications, particularly as a basic material for the manufacturing of hydrogel wound dressings, were synthesized. Gallic acid (GA) was selected in this work to study whether the interpenetrating polymer networks (IPNs) synthesized can provide antioxidant properties given that this material is intended to be used as a potential wound dressing. The obtained IPN hydrogels showed improved mechanical properties in comparison with pristine gelatin network (net-GE), a porous structure, and good thermal stability for biological applications. The antioxidant capacity of the IPNs functionalized with GA was compared to Trolox standards, obtaining a radical scavenging activity (RSA%) equivalent to a Trolox concentration of 400 µM. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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22 pages, 6633 KiB

Open AccessArticle

Phosphazene-Containing Epoxy Resins Based on Bisphenol F with Enhanced Heat Resistance and Mechanical Properties: Synthesis and Properties

by Ilya V. Tarasov, Anastasiya V. Oboishchikova, Roman S. Borisov, Vyacheslav V. Kireev and Igor S. Sirotin

Polymers 2022, 14(21), 4547; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14214547 - 27 Oct 2022

Cited by 2 | Viewed by 2161

Abstract

Organophosphazenes are of interest due to the combination of increased mechanical and thermal properties of polymer materials obtained with their use, however, they are characterized by a complex multi-stage synthesis. Moreover, the high viscosity of phosphazene-containing epoxy resins (PhER) makes their processing difficult. [...] Read more.

Organophosphazenes are of interest due to the combination of increased mechanical and thermal properties of polymer materials obtained with their use, however, they are characterized by a complex multi-stage synthesis. Moreover, the high viscosity of phosphazene-containing epoxy resins (PhER) makes their processing difficult. To simplify the synthesis of PhER, a one-step method was developed, and bisphenol F was chosen, which also provided a decrease in viscosity. In the current study, PhER were formed by a one-stage interaction of hexachlorocyclotriphosphazene (HCP) with bisphenol F isomers and epichlorohydrin in the presence of alkali, which was a mixture of epoxycyclophosphazenes (ECPh) with a functionality from 1 to 4 according to the results of MALDI-TOF analysis. Conventional epoxy resins based on bisphenol F, also formed during the process, showed high mechanical properties and glass transition temperature, and the reactivity of the obtained resins is similar to the base epoxy resins based on bisphenols A and F. Cured PhER had higher or the same mechanical properties compared to base epoxy resins based on bisphenol A and F, and a glass transition temperature comparable to base epoxy resins based on bisphenol F: glass transition temperature (Tg) up to 174.5 °C, tensile strength up to 74.5 MPa, tensile modulus up to 2050 MPa, tensile elongation at break up to 6.22%, flexural strength up to 146.6 MPa, flexural modulus up to 3630 MPa, flexural elongation at break up to 9.15%, and Izod impact strength up to 4.01 kJ/m². Analysis of the composition of the obtained PhER was carried out by ¹H and ³¹P NMR spectroscopy, MALDI-TOF mass spectrometry, X-ray fluorescence elemental analysis, and contained up to 3.9% phosphorus and from 1.3% to 4.2% chlorine. The temperature profile of the viscosity of the resulting epoxy resins was determined, and the viscosity at 25 °C ranged from 20,000 to 450,000 Pa·s, depending on the ratio of reagents. The resins studied in this work can be cured with conventional curing agents and, with a low content of the phosphazene fraction, can act as modifiers for traditional epoxy resins, being compatible with them, to increase impact strength and elasticity while maintaining the rest of the main mechanical and processing properties, and can be used as a resin component for composite materials, adhesives, and paints. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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16 pages, 2907 KiB

Open AccessArticle

Novel Therapeutic Approach in PEGylated Chitosan Nanoparticles of Apigenin for the Treatment of Cancer via Oral Nanomedicine

by Md Ali Mujtaba, Nawaf M. Alotaibi, Sultan M. Alshehri, Mohammad Yusuf, Md Khalid Anwer, Mohammad Akhlaquer Rahman and Arshiya Parveen

Polymers 2022, 14(20), 4344; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14204344 - 15 Oct 2022

Cited by 7 | Viewed by 1547

Abstract

The goal of this study was to optimize and formulate apigenin (APG)-loaded pegylated chitosan nanoparticles (PEGylated-CNPs) via ionic gelation techniques using the Box–Behnken design (BBD). Three individual variables, X₁(chitosan: TPP concentration), X₂ (PEG-400 concentration), and X₃ (sonication time), were [...] Read more.

The goal of this study was to optimize and formulate apigenin (APG)-loaded pegylated chitosan nanoparticles (PEGylated-CNPs) via ionic gelation techniques using the Box–Behnken design (BBD). Three individual variables, X₁(chitosan: TPP concentration), X₂ (PEG-400 concentration), and X₃ (sonication time), were investigated for their influence on response variables (Y₁—particle size (PS); Y₂—drug entrapment efficiency (DEE); and Y₃—zeta potential (ZP). The optimized formula of APG-PEGylated CNPs was picked from the statistical design and was then examined for physical, morphological, release characterization, anti-oxidant, and anti-tumor potential. The average PS, PDI, %DEE, and ZP were found to be 139.63 ± 5.67 nm, 0.296 ± 0.014, 79.55 ± 3.12%, and 24.68 ± 1.84 mV, respectively. The optimized APG formulation was chosen and reformulated based on the desirability function. Results of the observed and predicted values of responses through the BBD process were found to be nearly identical. The resulting APG-PEGylated CNPs were spherical and smooth, according to surface morphology studies. The release study revealed that PEGylated-CNPs exhibited biphasic release patterns distinguished by an initial burst release of APG only at early phases accompanied by a delayed release near 24 h. Furthermore, APG-PEGylated CNPs demonstrated statistically increased antioxidant activities and cytotoxicity against MCF-7 cells compared to pure APG. Based on the findings, it is possible to conclude that BBD was efficient in optimizing the PEGylated CNPs formulation and recognizing the impacts of formulation variables. In conclusion, the developed formulation has a significant potential for anticancer therapy. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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13 pages, 3982 KiB

Open AccessArticle

Development of Biodegradable Polyesters: Study of Variations in Their Morphological and Thermal Properties through Changes in Composition of Alkyl-Substituted (ε-DL) and Non-Substituted (ε-CL, EB, L-LA) Monomers

by Felipe Robles-González, Teresa Rodríguez-Hernández, Antonio S. Ledezma-Pérez, Ramón Díaz de León, Marco A. De Jesús-Téllez and Héctor Ricardo López-González

Polymers 2022, 14(20), 4278; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14204278 - 12 Oct 2022

Cited by 1 | Viewed by 1455

Abstract

Three series of polyesters based on monomer combinations of ε-caprolactone (ε-CL), ethylene brassylate (EB), and l-Lactide (LLA) with the alkyl substituted lactone ε-decalactone (ε-DL) were synthesized at different molar ratios. Copolymers were obtained via ring opening [...] Read more.

Three series of polyesters based on monomer combinations of ε-caprolactone (ε-CL), ethylene brassylate (EB), and l-Lactide (LLA) with the alkyl substituted lactone ε-decalactone (ε-DL) were synthesized at different molar ratios. Copolymers were obtained via ring opening polymerization (ROP) employing TBD (1,5,7-triazabicyclo-[4.4.0]-dec-5-ene), an organic catalyst which can be handled under normal conditions, avoiding the use of glove box equipment. The molar monomer composition of resulting copolymers differed from theoretical values due to lower ε-DL reactivity; their M_n and M_w values were up to 14 kDa and 22.8 kDa, respectively, and distributions were (Ɖ) ≤ 2.57. The thermal stability of these materials suffered due to variations in their ε-DL molar content. Thermal transitions such as melting (T_m) and crystallization (T_c) showed a decreasing tendency as ε-DL molar content increased, while glass transition (T_g) exhibited minor changes. It is worth mentioning that changes in monomer composition in these polyesters have a strong impact on their thermal performance, as well as in their crystallization degree. Consequently, variations in their chemical structure may have an effect on hydrolyic degradation rates. It should be noted that, in future research, some of these copolymers will be exposed to hydrolytic degradation experiments, including characterizations of their mechanical properties, to determine their adequacy in potential use in the development of soft medical devices. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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17 pages, 3990 KiB

Open AccessArticle

Improvement of the Polyhydroxyalkanoates Recovery from Mixed Microbial Cultures Using Sodium Hypochlorite Pre-Treatment Coupled with Solvent Extraction

by Gabriela Montiel-Jarillo, Diego A. Morales-Urrea, Edgardo M. Contreras, Alex López-Córdoba, Edwin Yesid Gómez-Pachón, Julián Carrera and María Eugenia Suárez-Ojeda

Polymers 2022, 14(19), 3938; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14193938 - 21 Sep 2022

Cited by 3 | Viewed by 2020

Abstract

The use of mixed microbial cultures (MMC) and organic wastes and wastewaters as feed sources is considered an appealing approach to reduce the current polyhydroxyalkanoates (PHAs) production costs. However, this method entails an additional hurdle to the PHAs downstream processing (recovery and purification). [...] Read more.

The use of mixed microbial cultures (MMC) and organic wastes and wastewaters as feed sources is considered an appealing approach to reduce the current polyhydroxyalkanoates (PHAs) production costs. However, this method entails an additional hurdle to the PHAs downstream processing (recovery and purification). In the current work, the effect of a sodium hypochlorite (NaClO) pre-treatment coupled with dimethyl carbonate (DMC) or chloroform (CF) as extraction solvents on the PHAs recovery efficiency (RE) from MMC was evaluated. MMC were harvested from a sequencing batch reactor (SBR) fed with a synthetic prefermented olive mill wastewaster. Two different carbon-sources (acetic acid and acetic/propionic acids) were employed during the batch accumulation of polyhydroxybutyrate (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) from MMC. Obtained PHAs were characterized by ¹H and ¹³C nuclear magnetic resonance, gel-permeation chromatography, differential scanning calorimetry, and thermal gravimetric analysis. The results showed that when a NaClO pre-treatment is not added, the use of DMC allows to obtain higher RE of both biopolymers (PHB and PHBV), in comparison with CF. In contrast, the use of CF as extraction solvent required a pre-treatment step to improve the PHB and PHBV recovery. In all cases, RE values were higher for PHBV than for PHB. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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25 pages, 15295 KiB

Open AccessArticle

Development and Mechano-Chemical Characterization of Polymer Composite Sheets Filled with Silica Microparticles with Potential in Printing Industry

by Sidra Siraj, Ali H. Al-Marzouqi and Muhammad Z. Iqbal

Polymers 2022, 14(16), 3351; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14163351 - 17 Aug 2022

Cited by 1 | Viewed by 1433

Abstract

Polymer composite sheets using a low-cost filler (local natural sand) and polymer (high-density polyethylene, HDPE) as a replacement of the traditionally used wood-fiber-based sheets for paper-based applications were developed. The sand/polymer composite sheets were prepared by melt extrusion in a melt blender followed [...] Read more.

Polymer composite sheets using a low-cost filler (local natural sand) and polymer (high-density polyethylene, HDPE) as a replacement of the traditionally used wood-fiber-based sheets for paper-based applications were developed. The sand/polymer composite sheets were prepared by melt extrusion in a melt blender followed by compression molding. The effects of varying particle size, concentration, and the use of a compatibilizer (polyethylene-grafted maleic anhydride) was studied on the mechano-chemical performance properties of the composite sheets such as morphology, thermal and mechanical properties, and wettability characteristics used in the printing industry. In terms of thermal stability, filler (sand) or compatibilizer addition did not alter the crystallization, melting, or degradation temperatures significantly, thereby promoting good thermal stability of the prepared sheets. Compatibilization improved anti-wetting property with water. Additionally, for the compatibilized sheets prepared from 25 µm sand particles, at 35 wt%, the contact angle with printing ink decreased from 44° to 38.30°, suggesting improved ink-wetting performance. A decrease in the elastic modulus was also observed with the addition of the compatibilizer, with comparable results to commercial stone paper. Results from this study will be considered as a first step towards understanding compatibility of local natural sand and polymers for paper-based application. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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13 pages, 2354 KiB

Open AccessArticle

Synthesis and Properties of Thermally Self-Healing PET Based Linear Polyurethane Containing Diels–Alder Bonds

by Minghui Xu, Ning Liu, Hongchang Mo, Xianming Lu, Jinkang Dou and Bojun Tan

Polymers 2022, 14(16), 3334; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14163334 - 16 Aug 2022

Cited by 3 | Viewed by 1910

Abstract

A Diels–Alder (DA) bond containing poly(tetrahydrofuran)-co-(ethyleneoxide) (PET) based linear polyurethane (PET-DA-PU) was synthesized via a prepolymer process using PET as raw material, DA diol as chain extender agent, and toluene-2,4-diisocyanate (TDI) as coupling agent. The structure of PET-DA-PU was characterized by attenuated total [...] Read more.

A Diels–Alder (DA) bond containing poly(tetrahydrofuran)-co-(ethyleneoxide) (PET) based linear polyurethane (PET-DA-PU) was synthesized via a prepolymer process using PET as raw material, DA diol as chain extender agent, and toluene-2,4-diisocyanate (TDI) as coupling agent. The structure of PET-DA-PU was characterized by attenuated total reflectance-Fourier transform-infrared spectroscopy (ATR-FTIR), proton nuclear magnetic resonance spectrometry (¹H NMR) and carbon nuclear magnetic resonance spectrometry (¹³C NMR). The thermal performance and self-healing behavior of PET-DA-PU were investigated by differential scanning calorimetry (DSC), polarized optical microscope, universal testing machine, scanning electron microscopy (SEM) and NMR, respectively. The glass transition temperature of PET-DA-PU was found to be −59 °C. Under the heat treatment at 100 °C, the crack on PET-DA-PU film completely disappeared in 9 min, and the self-healing efficiency that was determined by the recovery of the largest tensile strength after being damaged and healed at 100 °C for 20 min can reach 89.1%. SEM images revealed the micro-cracks along with the blocky aggregated hard segments which were the important reasons for fracture. NMR spectroscopy indicated that the efficiency of retro DA reaction of PET-DA-PU was 70% after 20 min heating treatment at 100 °C. Moreover, the PET-DA-PU/Al/Na₂SO₄ composite was also prepared to simulate propellant formulation and investigated by universal testing machine and SEM; its healing efficiency was up to 87.8% under the same heat treatment process and exhibits good self-healing ability. Therefore, PET-DA-PU may serve as a promising thermally self-healing polymeric binder for future propellant formulations. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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15 pages, 3563 KiB

Open AccessArticle

Spatiotemporal Temperature Distribution of NIR Irradiated Polypyrrole Nanoparticles and Effects of pH

by Omar Peñuñuri-Miranda, Miguel Olivas-Martinez, José Alberto Ibarra-Espinoza, Rosalva Josefina Rodríguez-Córdova, Karol Yesenia Hernández-Giottonini, Daniel Fernández-Quiroz, Paul Zavala-Rivera and Armando Lucero-Acuña

Polymers 2022, 14(15), 3151; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14153151 - 02 Aug 2022

Viewed by 1322

Abstract

The spatiotemporal temperature distributions of NIR irradiated polypyrrole nanoparticles (PPN) were evaluated by varying PPN concentrations and the pH of suspensions. The PPN were synthesized by oxidative chemical polymerization, resulting in a hydrodynamic diameter of 98 ± 2 nm, which is maintained in [...] Read more.

The spatiotemporal temperature distributions of NIR irradiated polypyrrole nanoparticles (PPN) were evaluated by varying PPN concentrations and the pH of suspensions. The PPN were synthesized by oxidative chemical polymerization, resulting in a hydrodynamic diameter of 98 ± 2 nm, which is maintained in the pH range of 4.2–10; while the zeta potential is significantly affected, decreasing from 20 ± 2 mV to −5 ± 1 mV at the same pH range. The temperature profiles of PPN suspensions were obtained using a NIR laser beam (1.5 W centered at 808 nm). These results were analyzed with a three-dimensional predictive unsteady-state heat transfer model that considers heat conduction, photothermal heating from laser irradiation, and heat generation due to the water absorption. The temperature profiles of PPN under laser irradiation are concentration-dependent, while the pH increase only induces a slight reduction in the temperature profiles. The model predicts a value of photothermal transduction efficiency (

η

) of 0.68 for the PPN. Furthermore, a linear dependency was found for the overall heat transfer coefficient (

U

) and

η

with the suspension temperature and pH, respectively. Finally, the model developed in this work could help identify the exposure time and concentration doses for different tissues and cells (pH-dependent) in photothermal applications. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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17 pages, 4160 KiB

Open AccessArticle

A New Approach Utilizing Aza-Michael Addition for Hydrolysis-Resistance Non-Ionic Waterborne Polyester

by Hao Fu, Linbo Gong and Shuling Gong

Polymers 2022, 14(13), 2655; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14132655 - 29 Jun 2022

Cited by 3 | Viewed by 1734

Abstract

This work first synthesized a series of linear polyesters by step-growth polycondensation, then an amino-terminated hydrophilic polyether was grafted to the polyester as side-chains through aza-Michael addition to prepare a self-dispersible, non-ionic waterborne comb-like polyester (NWCPE). In contrast to traditional functionalization methods that [...] Read more.

This work first synthesized a series of linear polyesters by step-growth polycondensation, then an amino-terminated hydrophilic polyether was grafted to the polyester as side-chains through aza-Michael addition to prepare a self-dispersible, non-ionic waterborne comb-like polyester (NWCPE). In contrast to traditional functionalization methods that usually require harsh reaction conditions and complex catalysts, the aza-Michael addition proceeds efficiently at room temperature without a catalyst. In this facile and mild way, the NWCPE samples with number-average molecular weight (M_n) of about 8000 g mol⁻¹ were obtained. All dispersions showed excellent storage stability, reflected by no delamination observed after 6 months of storage. The NWCPE dispersion displayed better hydrolysis resistance than an ionic waterborne polyester, as was indicated by a more slight change in pH value and M_n after a period of storage. In addition, the film obtained after the NWCPE dispersion was cross-linked with the curing agent, it exhibited good water resistance, adhesion, and mechanical properties. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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16 pages, 4790 KiB

Open AccessArticle

Synthesis and Study of Physical and Mechanical Properties of Urethane-Containing Elastomers Based on Epoxyurethane Oligomers with Controlled Crystallinity

by Alexey Slobodinyuk, Vladimir Strelnikov, Nadezhda Elchisheva, Dmitriy Kiselkov and Daria Slobodinyuk

Polymers 2022, 14(11), 2136; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14112136 - 24 May 2022

Cited by 2 | Viewed by 1528

Abstract

The influence of the molecular weight of oligoamine, oligoether, and the type of diisocyanate on the physical and mechanical properties of elastomers with urethane hydroxyl hard segments was studied. For this purpose, oligoetherdiamines with molecular weights ~1008 and ~1400 g mol⁻¹ were [...] Read more.

The influence of the molecular weight of oligoamine, oligoether, and the type of diisocyanate on the physical and mechanical properties of elastomers with urethane hydroxyl hard segments was studied. For this purpose, oligoetherdiamines with molecular weights ~1008 and ~1400 g mol⁻¹ were synthesized by a three-stage method. Epoxyurethane oligomers were synthesized according to a two-step route with an oligodiisocyanate as an intermediate product. A series of 12 elastomers with controlled crystallinity were synthesized from these elastomers and amines. The deformation and strength properties of the elastomers were studied. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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18 pages, 3453 KiB

Open AccessArticle

Mathematical Description of the RAFT Copolymerization of Styrene and Glycidyl Methacrylate Using the Terminal Model

by José Alfredo Tenorio-López, Juan José Benvenuta-Tapia, Norma García-Navarro, Eduardo Vivaldo-Lima, Pascale Champagne and Enrique Saldívar-Guerra

Polymers 2022, 14(7), 1448; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14071448 - 01 Apr 2022

Cited by 1 | Viewed by 2018

Abstract

A mathematical model for the kinetics, composition and molar mass development of the bulk reversible addition-fragmentation chain transfer (RAFT) copolymerization of glycidyl methacrylate (GMA) and styrene (St), at several GMA molar feed fractions at 103 °C, in the presence of 2-cyano isopropyl dodecyl [...] Read more.

A mathematical model for the kinetics, composition and molar mass development of the bulk reversible addition-fragmentation chain transfer (RAFT) copolymerization of glycidyl methacrylate (GMA) and styrene (St), at several GMA molar feed fractions at 103 °C, in the presence of 2-cyano isopropyl dodecyl trithiocarbonate as the RAFT agent and 1,1′-azobis(cyclohexane carbonitrile), as the initiator, is presented. The copolymerization proceeded in a controlled manner and dispersities of the copolymers remained narrow even at high conversions. Experimental data and calculated profiles of conversion versus time, composition versus conversion and molar mass development for the RAFT copolymerization of St and GMA agreed well for all conditions tested, including high-conversion regions. The kinetic rate constants associated with the RAFT- related reactions and diffusion-controlled parameters were properly estimated using a weighted nonlinear multivariable regression procedure. The mathematical model developed in this study may be used as an aid in the design and upscaling of industrial RAFT polymerization processes. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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19 pages, 16908 KiB

Open AccessArticle

Characterization of a Radiofluorogenic Polymer for Low-Energy Electron Beam Penetration Depth Visualization

by Magdalena Maria Skowyra, Christina Ankjærgaard, Liyun Yu, Lars René Lindvold, Anne Ladegaard Skov and Arne Miller

Polymers 2022, 14(5), 1015; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14051015 - 03 Mar 2022

Viewed by 2006

Abstract

Low-energy (80–300 keV) electron beam accelerators are gaining in importance in the radiation processing industry due to their ease of use and wide range of applications (e.g. product surface sterilizations or polymer curing and cross-linking). Due to their very low penetration depth (tens [...] Read more.

Low-energy (80–300 keV) electron beam accelerators are gaining in importance in the radiation processing industry due to their ease of use and wide range of applications (e.g. product surface sterilizations or polymer curing and cross-linking). Due to their very low penetration depth (tens to hundreds of microns), currently used film dosimeters exhibit dose gradients over their thickness and do not resolve the dose response in the first microns of the irradiated material. Hence, the surface dose, defined as the dose in the first micron D_µ, cannot be measured directly. This study presents a polymer material as a dosimeter candidate for high-dose low-energy electron beam irradiations. The readout of the dose-dependent fluorescence intensity, originating from a pararosaniline dye reaction when irradiated, is measured using fluorescence microscopy. So far, no in-depth characterization of the material has been performed, leaving the stability and fluorescence properties of the material not fully optimized. We describe the improvements in polymer composition and the fabrication method, and characterize the material properties in terms of the thermal stability, glass transition temperature, refractive index, hardness, rheological behavior, and water affinity. All of these create a complex set of requirements a polymer needs to fulfill to become an effective dosimeter when measuring using confocal microscopy. The fluorescence readout procedure will be addressed in further studies. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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20 pages, 6583 KiB

Open AccessArticle

Tuning the Morphology in the Nanoscale of NH₄CN Polymers Synthesized by Microwave Radiation: A Comparative Study

by Cristina Pérez-Fernández, Pilar Valles, Elena González-Toril, Eva Mateo-Martí, José Luis de la Fuente and Marta Ruiz-Bermejo

Polymers 2022, 14(1), 57; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14010057 - 24 Dec 2021

Cited by 6 | Viewed by 2474

Abstract

A systematic study is presented to explore the NH₄CN polymerization induced by microwave (MW) radiation, keeping in mind the recent growing interest in these polymers in material science. Thus, a first approach through two series, varying the reaction times and the [...] Read more.

A systematic study is presented to explore the NH₄CN polymerization induced by microwave (MW) radiation, keeping in mind the recent growing interest in these polymers in material science. Thus, a first approach through two series, varying the reaction times and the temperatures between 130 and 205 °C, was conducted. As a relevant outcome, using particular reaction conditions, polymer conversions similar to those obtained by means of conventional thermal methods were achieved, with the advantage of a very significant reduction of the reaction times. The structural properties of the end products were evaluated using compositional data, spectroscopic measurements, simultaneous thermal analysis (STA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). As a result, based on the principal component analysis (PCA) from the main experimental results collected, practically only the crystallographic features and the morphologies in the nanoscale were affected by the MW-driven polymerization conditions with respect to those obtained by classical syntheses. Therefore, MW radiation allows us to tune the morphology, size and shape of the particles from the bidimensional C=N networks which are characteristic of the NH₄CN polymers by an easy, fast, low-cost and green-solvent production. These new insights make these macromolecular systems attractive for exploration in current soft-matter science. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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16 pages, 3990 KiB

Open AccessArticle

Influence of Oligopeptide Length and Distribution on Polyisoprene Properties

by Chang-Cheng Wang, Rong Zhang, Shiqi Li, Guangsu Huang, Maozhu Tang and Yun-Xiang Xu

Polymers 2021, 13(24), 4408; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13244408 - 15 Dec 2021

Cited by 1 | Viewed by 1981

Abstract

The tuning of binding modes of polar groups is the key step to mimicking the structure and properties of natural rubber through the molecular design of synthetic polyisoprenes. Herein, the ordering and binding distances of oligopeptides could be altered systematically by changing their [...] Read more.

The tuning of binding modes of polar groups is the key step to mimicking the structure and properties of natural rubber through the molecular design of synthetic polyisoprenes. Herein, the ordering and binding distances of oligopeptides could be altered systematically by changing their lengths and distribution along the polyisoprene chain, which impose huge impacts on the mechanical properties and chain dynamics of green rubber. In detail, a series of peptide-functionalized polyisoprenes with terminal blocks (B-2A-PIP, B-3A-PIP) or random sequences (R-2A-PIP, R-3A-PIP) are fabricated by using dipeptides (2A) or tripeptides (3A) as crosslinkers to explore the mechanism of terminal interaction on mechanism properties and chain dynamics. B-4A-PIP and R-4A-PIP served as control samples. It is found that the increased oligopeptide length and the block distribution improves the mechanical properties and confine the chain movement by elevate the contents of ordered and compact microstructures, which is indicated by XRD, broadband dielectric spectroscopy (BDS) and consistent with the result of molecular dynamics simulation. New relaxation signals belonging to oligopeptide aggregates are found which showed elevated dielectric strengths upon temperatures increase. Additionally, it also reveals that the binding modes of oligopeptide do not significantly influence the entanglements of polyisoprene. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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22 pages, 4747 KiB

Open AccessArticle

Strippable Polymeric Nanocomposites Comprising “Green” Chelates, for the Removal of Heavy Metals and Radionuclides

by Gabriela Toader, Daniela Pulpea, Traian Rotariu, Aurel Diacon, Edina Rusen, Andreea Moldovan, Alice Podaru, Raluca Ginghină, Florentina Alexe, Ovidiu Iorga, Sorina Aurora Bajenaru, Mihai Ungureanu, Florin Dîrloman, Bogdan Pulpea and Lucia Leonat

Polymers 2021, 13(23), 4194; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13234194 - 30 Nov 2021

Cited by 5 | Viewed by 1930

Abstract

The issue of heavy metal and radionuclide contamination is still causing a great deal of concern worldwide for environmental protection and industrial sites remediation. Various techniques have been developed for surface decontamination aiming for high decontamination factors (DF) and minimal environmental impact, but [...] Read more.

The issue of heavy metal and radionuclide contamination is still causing a great deal of concern worldwide for environmental protection and industrial sites remediation. Various techniques have been developed for surface decontamination aiming for high decontamination factors (DF) and minimal environmental impact, but strippable polymeric nanocomposite coatings are some of the best candidates in this area. In this study, novel strippable coatings for heavy metal and radionuclides decontamination were developed based on the film-forming ability of polyvinyl alcohol, with the remarkable metal retention capacity of bentonite nanoclay, together with the chelating ability of sodium alginate and with “new-generation” “green” complexing agents: iminodisuccinic acid (IDS) and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC). These environmentally friendly water-based decontamination solutions are capable of generating strippable polymeric films with optimized mechanical and thermal properties while exhibiting high decontamination efficiency (DF ≈ 95–98% for heavy metals tested on glass surface and DF ≈ 91–97% for radionuclides ²⁴¹Am, ⁹⁰Sr-Y and ¹³⁷Cs on metal, painted metal, plastic, and glass surfaces). Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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17 pages, 4521 KiB

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A Novel Approach of Bioesters Synthesis through Different Technologies by Highlighting the Lowest Energetic Consumption One

by Simona Popa, Andra Tamas, Vasile Simulescu, Dorin Jurcau, Sorina Boran and Giannin Mosoarca

Polymers 2021, 13(23), 4190; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13234190 - 30 Nov 2021

Viewed by 1486

Abstract

Fatty acids esters have a wide application as bioplasticizers and biolubricants in different industries, obtained mainly in classic batch reactors, through an equilibrium complex reaction, that involves high temperatures, long reaction times, vigorously stirring, and much energy consumption. To overcome these shortcomings, we [...] Read more.

Fatty acids esters have a wide application as bioplasticizers and biolubricants in different industries, obtained mainly in classic batch reactors, through an equilibrium complex reaction, that involves high temperatures, long reaction times, vigorously stirring, and much energy consumption. To overcome these shortcomings, we synthesized a series of fatty acid esters (soybean oil fatty acids being the acid components with various hydroxyl compounds) through novel low energy consumption technologies using a bubble column reactor, a microwave field reactor and for comparison meaning, a classic batch reactor. The obtained bioesters physicochemical properties were similar to one another, a good concordance among their rheological properties was obtained, but the energetic consumption is lower when using the bubble column or the microwave reactors instead of the classical batch reactor. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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13 pages, 4125 KiB

Open AccessArticle

Removal of Trithiocarbonyl End Group of RAFT-Polymerized Poly(stearyl acrylate) and Effect of the End Group on Thermal and Structural Properties

by Eri Oishi, Masumi Takamura and Tatsuhiro Takahashi

Polymers 2021, 13(23), 4169; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13234169 - 28 Nov 2021

Cited by 3 | Viewed by 2175

Abstract

The effect of a long alkyl end group on the thermal and structural properties of RAFT (reversible addition-fragmentation chain transfer)-polymerized poly(stearyl acrylate) (PSA) was investigated. RAFT-polymerized PSA was prepared using 2-cyano-2-[(dodecylsulfanylthiocarbonyl) sulfanyl] propane (CDTP) with long alkyl group as a chain transfer agent [...] Read more.

The effect of a long alkyl end group on the thermal and structural properties of RAFT (reversible addition-fragmentation chain transfer)-polymerized poly(stearyl acrylate) (PSA) was investigated. RAFT-polymerized PSA was prepared using 2-cyano-2-[(dodecylsulfanylthiocarbonyl) sulfanyl] propane (CDTP) with long alkyl group as a chain transfer agent and azobisisobutyronitrile (AIBN) as an initiator. The RAFT polymerization resulted in the polymerized structure having trithiocarbonyl (TTC) at one end and isobutyronitrile at the other end. RAFT-polymerized PSA was prepared with two different molecular weights. The TTC end group was replaced by isobutyronitrile using radical reaction with AIBN through optimization of the conditions, which resulted in isobutyronitrile at both ends. The effect of the end group on the thermal and structural properties was investigated using differential scanning calorimetry and X-ray diffraction, and the results indicated that the long alkyl group from TTC lowers the melting point and semi-crystalline structure in the case of low molecular weight PSA. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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27 pages, 9816 KiB

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Eco–Friendly Peelable Active Nanocomposite Films Designed for Biological and Chemical Warfare Agents Decontamination

by Gabriela Toader, Aurel Diacon, Traian Rotariu, Mioara Alexandru, Edina Rusen, Raluca Elena Ginghină, Florentina Alexe, Ramona Oncioiu, Florina Lucica Zorila, Alice Podaru, Andreea Elena Moldovan, Daniela Pulpea, Ana Mihaela Gavrilă, Tanta Verona Iordache and Raluca Șomoghi

Polymers 2021, 13(22), 3999; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13223999 - 19 Nov 2021

Cited by 8 | Viewed by 3245

Abstract

In the context of imminent threats concerning biological and chemical warfare agents, the aim of this study was the development of a new method for biological and chemical decontamination, employing non-toxic, film-forming, water-based biodegradable solutions, using a nano sized reagent together with bentonite [...] Read more.

In the context of imminent threats concerning biological and chemical warfare agents, the aim of this study was the development of a new method for biological and chemical decontamination, employing non-toxic, film-forming, water-based biodegradable solutions, using a nano sized reagent together with bentonite as trapping agents for the biological and chemical contaminants. Bentonite-supported nanoparticles of Cu, TiO₂, and Ag were successfully synthesized and dispersed in a polyvinyl alcohol (PVA)/glycerol (GLY) aqueous solution. The decontamination effectiveness of the proposed solutions was evaluated by qualitative and quantitative analytical techniques on various micro-organisms, with sulfur mustard (HD) and dimethyl methylphosphonate (DMMP) as contaminants. The results indicate that the peelable active nanocomposite films can be successfully used on contaminated surfaces to neutralize and entrap the hazardous materials and their degradation products. Mechanical and thermal characterization of the polymeric films was also performed to validate the decontamination solution’s potential as peelable-film generating materials. The removal efficacy from the contaminated surfaces for the tested micro-organisms varied between 93% and 97%, while for the chemical agent HD, the highest decontamination factor obtained was 90.89%. DMMP was almost completely removed from the contaminated surfaces, and a decontamination factor of 99.97% was obtained. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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28 pages, 7275 KiB

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Novel Polyurethanes Based on Recycled Polyethylene Terephthalate: Synthesis, Characterization, and Formulation of Binders for Environmentally Responsible Rocket Propellants

by Florin Marian Dîrloman, Gabriela Toader, Traian Rotariu, Tudor Viorel Țigănescu, Raluca Elena Ginghină, Răzvan Petre, Florentina Alexe, Mihai Ionuț Ungureanu, Edina Rusen, Aurel Diacon, Adi Ghebaur, Monica Duldner, Alina Elena Coman and Robert Țincu

Polymers 2021, 13(21), 3828; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13213828 - 05 Nov 2021

Cited by 8 | Viewed by 3274

Abstract

Novel polyurethane-based binders, specifically designed for environmentally responsible rocket propellant composites, were obtained by employing the polyester-polyols that resulted from the degradation of polyethylene terephthalate waste. A new class of “greener” rocket propellants, comprising polyurethanes (based on recycled PET) as the binder, phase [...] Read more.

Novel polyurethane-based binders, specifically designed for environmentally responsible rocket propellant composites, were obtained by employing the polyester-polyols that resulted from the degradation of polyethylene terephthalate waste. A new class of “greener” rocket propellants, comprising polyurethanes (based on recycled PET) as the binder, phase stabilized ammonium nitrate (PSAN) as the eco-friendly oxidizer, and triethylene glycol dinitrate (TEGDN) as the energetic plasticizer, together with aluminum as fuel and Fe₂O₃ as the catalyst, is herein reported. The components of the energetic mixtures were investigated (individually and as composite materials) through specific analytical tools: ¹H-NMR, FT-IR, SEM-EDX, DTA and TGA, tensile and compression tests, DMA, and micro-CT. Moreover, the feasibility of this innovative solution is sustained by the ballistic performances exhibited by these composite materials in a subscale rocket motor, proving that these new formulations are suitable for rocket propellant applications. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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20 pages, 3416 KiB

Open AccessArticle

Biosynthesis of Poly-ß-Hydroxybutyrate (PHB) from Different Bacterial Strains Grown on Alternative Cheap Carbon Sources

by Sherif M. El-Kadi, Mohssen Elbagory, Hassan A. H. EL-Zawawy, Hossam F. A. EL-Shaer, Adel A. Shoukry, Sahar El-Nahrawy, Alaa El-Dein Omara and Dina Fathi Ismail Ali

Polymers 2021, 13(21), 3801; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13213801 - 03 Nov 2021

Cited by 14 | Viewed by 2663

Abstract

Thirty bacterial isolates were tested on three different media for Poly-ß-hydroxybutyrate (PHB) production. The best bacterial isolates for producing PHB were screened and identified based on molecular biology; then, using three different alternative carbon sources (dried whey, sugar beet molasses and date molasses), [...] Read more.

Thirty bacterial isolates were tested on three different media for Poly-ß-hydroxybutyrate (PHB) production. The best bacterial isolates for producing PHB were screened and identified based on molecular biology; then, using three different alternative carbon sources (dried whey, sugar beet molasses and date molasses), physical properties were evaluated by Infrared (IR) spectrometry and Gas chromatography–mass spectrometry (GC-MS/MS) analysis. Our results showed that the best isolates identified based on molecular biology were Bacillus paramycoides MCCC 1A04098, Azotobacter salinestris NBRC 102611 and Brevundimonas naejangsanensis BIO-TAS2-2. The addition of sugar beet molasses to the medium of A. salinestris increased the cell dry weight (CDW), PHB concentration, PHB% and conversion coefficient (4.97 g/L, 1.56 g/L, 31.38% and 23.92%, respectively). The correlation coefficient values between PHB g/L and CDW g/L varied between very strong and moderate positive correlation. IR of the produced PHB from B. paramycoides and A. salinestris showed similar bands which confirmed the presence of PHB; however, B. naejangsanensis showed weak bands, indicating lower PHB concentration. The chemical composition obtained showed that the GC-MS of the PHB extracted represents 2, 4-ditert-butylphenol for B. paramycoides and isopropyl ester of 2-butenoic acid for both of A. salinestris and Brevundimonas naejangsanensis. Therefore, PHB produced by microorganisms can be considered a biodegradable polyester, and represents a promising technique for the development of eco-friendly and fully biodegradable plastics. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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17 pages, 10022 KiB

Open AccessArticle

Synthesis and Study of Morphology and Biocompatibility of Xanthan Gum/Titanium Dioxide-Based Polyurethane Elastomers

by Shazia Naheed, Muhammad Shahid, Rashida Zahoor, Zumaira Siddique, Nasir Rasool, Sajjad Haider and Shaukat Khan

Polymers 2021, 13(19), 3416; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13193416 - 05 Oct 2021

Cited by 5 | Viewed by 1690

Abstract

A series of xanthan gum/titanium dioxide-based polyurethane elastomers were synthesized through the prepolymer method by the step growth polymerization. In the present work, xanthan gum was used as a bioactive material, with TiO₂ as a nanofiller. The structural characterization of newly prepared [...] Read more.

A series of xanthan gum/titanium dioxide-based polyurethane elastomers were synthesized through the prepolymer method by the step growth polymerization. In the present work, xanthan gum was used as a bioactive material, with TiO₂ as a nanofiller. The structural characterization of newly prepared polyurethane samples was carried out with the help of Fourier Transform Infrared Spectroscopy. Thermogravimetric Analysis gave us the information about the thermal stability. Differential Scanning Calorimetry directs the thermal changes in the polyurethane samples. The Atomic Force Microscopy technique revealed that the degree of micro-phase separation increases by augmenting the % age of TiO₂, which was further confirmed by X-Ray Diffraction results. XRD confirmed the crystallinity of the final sample at about 2θ = 20°. Antimicrobial activity determined through the Disc Diffusion Method, and the results indicated that the synthesized polyurethane have antimicrobial activity. The water absorption capability of the polyurethane samples showed that these polymer samples are hydrophilic in nature. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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25 pages, 3715 KiB

Open AccessArticle

Preparation of Emulsifier-Free Styrene–Acrylic Emulsion via Reverse Iodine Transfer Polymerization

by Tao Huang and Shuling Gong

Polymers 2021, 13(19), 3348; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13193348 - 29 Sep 2021

Cited by 4 | Viewed by 3301

Abstract

Styrene–acrylic emulsions containing hydroxyl functional monomer unit’s component are widely used for maintenance coating. In this paper, a stable emulsifier-free styrene–acrylic emulsion with solid content over 43% could be obtained in 210 min via reverse iodine transfer polymerization (RITP). By adding a mixture [...] Read more.

Styrene–acrylic emulsions containing hydroxyl functional monomer unit’s component are widely used for maintenance coating. In this paper, a stable emulsifier-free styrene–acrylic emulsion with solid content over 43% could be obtained in 210 min via reverse iodine transfer polymerization (RITP). By adding a mixture of methacrylic acid (MAA) and poly(ethylene glycol)methyl ether methacrylate (PEGMA) into a system containing a high content of hydroxyl functional monomer component (19.4 wt.% of the total monomer mass), styrene (St) could be copolymerized with methyl methacrylate (MMA); the modified film exhibited good hardness properties, good adhesive properties, and low water absorption. An increase in the amount of PEGMA decreased the glass transition temperature (T_g). When 1.4 times the reference amount of initiator was added, the highest molecular weight M_n could reach 40,000 g.·mol⁻¹ with 0.25 times the reference amount of iodine in the emulsion. The largest tensile strength of the dried emulsion film over 5.5 MPa endowed the material with good mechanical properties. Living polymerization was proven by the kinetics of RITP emulsion and chain extension reaction. TEM micrographs manifest the emulsification of the seed random copolymer. This paper may provide a potential methodology for preparing polymer materials with excellent mechanical properties. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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11 pages, 2825 KiB

Open AccessArticle

cis-1,4 Selective Coordination Polymerization of 1,3-Butadiene and Copolymerization with Polar 2-(4-Methoxyphenyl)-1,3-butadiene by Acenaphthene-Based α-Diimine Cobalt Complexes Featuring Intra-Ligand π-π Stacking Interactions

by Beibei Wang, Heng Liu, Tao Tang and Xuequan Zhang

Polymers 2021, 13(19), 3329; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13193329 - 29 Sep 2021

Cited by 2 | Viewed by 1770

Abstract

Highly cis-1,4 selective (up to 98%) coordination–insertion polymerization of 1,3-butadiene (BD) has been achieved herein using acenaphthene-based α-diimine cobalt complexes. Due to the presence of intra-ligand π-π stacking interactions, the complexes revealed high thermostability, affording polybutadiene products in high yields. Moreover, [...] Read more.

Highly cis-1,4 selective (up to 98%) coordination–insertion polymerization of 1,3-butadiene (BD) has been achieved herein using acenaphthene-based α-diimine cobalt complexes. Due to the presence of intra-ligand π-π stacking interactions, the complexes revealed high thermostability, affording polybutadiene products in high yields. Moreover, all of the obtained polymers possessed a relatively narrow molecular weight distribution as well as high molecular weight (up to 92.2 × 10⁴ Dalton). The molecular weights of the resultant polybutadienes could be finely tuned by varying polymerization parameters, including temperature, Al/Co ratio, etc. Moreover, the copolymerization of butadiene with polar monomer 2-(4-methoxyphenyl)-1,3-butadiene (2-MOPB) was also successfully realized to produce a type of polar cis-1,4 polybutadiene (cis-1,4 content: up to 98.1%) with a range of 2-MOPB content (0.46–1.83%). Water contact angle measurements indicated that the insertion of a polar monomer into a polymer chain could significantly improve the polymer’s surface property. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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19 pages, 4937 KiB

Open AccessArticle

Molecular Brushes with a Polyimide Backbone and Poly(ε-Caprolactone) Side Chains by the Combination of ATRP, ROP, and CuAAC

by Anna V. Kashina, Tamara K. Meleshko, Natalia N. Bogorad, Viktor K. Lavrentyev and Alexander V. Yakimansky

Polymers 2021, 13(19), 3312; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13193312 - 28 Sep 2021

Cited by 1 | Viewed by 1921

Abstract

An approach to the synthesis of the novel molecular brushes with a polyimide (PI) backbone and poly(ε-caprolactone) (PCL) side chains was developed. To obtain such copolymers, a combination of various synthesis methods was used, including polycondensation, atom transfer radical polymerization (ATRP), ring opening [...] Read more.

An approach to the synthesis of the novel molecular brushes with a polyimide (PI) backbone and poly(ε-caprolactone) (PCL) side chains was developed. To obtain such copolymers, a combination of various synthesis methods was used, including polycondensation, atom transfer radical polymerization (ATRP), ring opening polymerization (ROP), and Cu (I)-catalyzed azide-alkyne Huisgen cycloaddition (CuAAC). ATRP of 2-hydroxyethyl methacrylate (HEMA) on PI macroinitiator followed by ROP of ε-caprolactone (CL) provided a “brush on brush” structure PI-g-(PHEMA-g-PCL). For the synthesis of PI-g-PCL two synthetic routes combining ROP and CuAAC were compared: (1) polymer-analogous transformations of a multicenter PI macroinitiator with an initiating hydroxyl group separated from the main chain by a triazole ring followed by ROP of CL, or (2) a separate synthesis of macromonomers with the desirable functional groups (polyimide with azide groups and PCL with terminal alkyne groups), followed by a click reaction. Results showed that the first approach allows to obtain graft copolymers with a PI backbone and relatively short PCL side chains. While the implementation of the second approach leads to a more significant increase in the molecular weight, but unreacted linear PCL remains in the system. Obtained macroinitiators and copolymers were characterized using ¹H NMR and IR spectroscopy, their molecular weight characteristics were determined by SEC with triple detection. TGA and DSC were used to determine their thermal properties. X-ray scattering data showed that the introduction of a polyimide block into the polycaprolactone matrix did not change the degree of crystallinity of PCL. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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18 pages, 8281 KiB

Open AccessArticle

The Influence of Substituents in Phosphazene Catalyst-Flame Retardant on the Thermochemistry of Benzoxazine Curing

by Natalia V. Bornosuz, Roman F. Korotkov, Alexander A. Kolenchenko, Alexey V. Shapagin, Alexey V. Orlov, Irina Yu. Gorbunova, Vyacheslav V. Kireev and Igor S. Sirotin

Polymers 2021, 13(18), 3111; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13183111 - 15 Sep 2021

Cited by 2 | Viewed by 1792

Abstract

This work is devoted to the influence of phosphazene modifiers with different substituents on the curing process, thermal properties and flammability of benzoxazine resin. Novel catalysts with m-toluidine substituents were introduced. The catalytic activity of studied phosphazene compounds decreased in the row: hexachlorocyclotriphosphazene [...] Read more.

This work is devoted to the influence of phosphazene modifiers with different substituents on the curing process, thermal properties and flammability of benzoxazine resin. Novel catalysts with m-toluidine substituents were introduced. The catalytic activity of studied phosphazene compounds decreased in the row: hexachlorocyclotriphosphazene (HCP) > tetra m-toluidine substituted phosphazene PN-mt (4) > hexa m-toluidine substituted phosphazene PN-mt (6) > hexaphenoxycyclotriphosphazene (HPP), where HPP is totally inactive. Two types of catalysis: basic and acid were proposed. A brief study of resulting properties of polybenzoxazines was presented. The addition of any studied modifier caused the decrease of glass transition temperature and thermal stability of polymers. The morphology of cured compositions was characterized by matrix-dispersion phase structure. All phosphazene containing polybenzoxazines demonstrated the improved flame resistance. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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15 pages, 2702 KiB

Open AccessArticle

Eight-Fold Interpenetrating Diamondoid Coordination Polymers for Sensing Volatile Organic Compounds and Metal Ions

by Venkatesan Lakshmanan, Yi-Ting Lai, Xiang-Kai Yang, Manivannan Govindaraj, Chia-Her Lin and Jhy-Der Chen

Polymers 2021, 13(18), 3018; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13183018 - 07 Sep 2021

Cited by 7 | Viewed by 1873

Abstract

Reactions of divalent metal salts with 4,4-oxybis(N-(pyridine-4-yl)-benzamide), L, and naphthalene-1,4-dicarboxylic acid (1,4-H₂NDC) in various solvents gave [Zn(L)(1,4-NDC)·H₂O]_n, 1, [Cd(L)(1,4-NDC)(H₂O)·MeOH]_n, 2, and [Co(L)(1,4-NDC)(H₂O) [...] Read more.

Reactions of divalent metal salts with 4,4-oxybis(N-(pyridine-4-yl)-benzamide), L, and naphthalene-1,4-dicarboxylic acid (1,4-H₂NDC) in various solvents gave [Zn(L)(1,4-NDC)·H₂O]_n, 1, [Cd(L)(1,4-NDC)(H₂O)·MeOH]_n, 2, and [Co(L)(1,4-NDC)(H₂O)_0.5·MeOH]_n, 3, which have been structurally characterized. Complexes 1–3 show eight-fold interpenetrating frameworks with the dia topology, which exhibit porosities substantiated by CO₂ adsorption, whereas 1 and 2 manifest stability in aqueous environments and show high selectivity toward sensing of mesitylene molecules and Fe³⁺ ions with low detection limits and good reusability up to five cycles. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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15 pages, 5092 KiB

Open AccessArticle

Experimental Study on High-Performers Quaternary Copolymer Based on Host–Guest Effect

by Tao Xu, Jincheng Mao, Yang Zhang, Xiaojiang Yang, Chong Lin, Anqi Du, Heng Zhang, Quan Zhang and Jinhua Mao

Polymers 2021, 13(17), 2972; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13172972 - 01 Sep 2021

Cited by 3 | Viewed by 1910

Abstract

A quaternary polymer (HGP) was prepared by the free-radical polymerization of acrylamide, acrylic acid, maleic anhydride functionalized β-cyclodextrin (MAH-β-CD), and N-(3-methacrylamidopropyl)-N, N-dimethylnaphthalen-1-aminium chloride (NAP). It was found that host–guest behavior occurred most effectively at a molar rate of NAP and [...] Read more.

A quaternary polymer (HGP) was prepared by the free-radical polymerization of acrylamide, acrylic acid, maleic anhydride functionalized β-cyclodextrin (MAH-β-CD), and N-(3-methacrylamidopropyl)-N, N-dimethylnaphthalen-1-aminium chloride (NAP). It was found that host–guest behavior occurred most effectively at a molar rate of NAP and CD with 1:1, which exhibited better solubility than hydrophobically associative polymer. Moreover, the as-prepared polymer has superior salt tolerance, shear resistance, and viscoelasticity due to host–guest strategy. More importantly, the HGP solution simulates the distribution of formation water in the Bohai SZ1-1 oilfield has good rheological properties at 120 °C. All results show that the proposed polymer could be a competitive candidate in oilfield applications such as fracturing fluids, displacement fluids, and drilling fluids. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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15 pages, 27836 KiB

Open AccessArticle

Preparation of Bisphenol-A and Polydimethylsiloxane (PDMS) Block Copolycarbonates by Melt Polycondensation: Effects of PDMS Chain Length on Conversion and Miscibility

by Zibo Zhou and Guozhang Wu

Polymers 2021, 13(16), 2660; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13162660 - 10 Aug 2021

Cited by 3 | Viewed by 3168

Abstract

This study aimed to improve polydimethylsiloxane (PDMS) conversion in the preparation of polycarbonate (PC)–polydimethylsiloxane (PDMS) copolymer through melt polycondensation. We examined the transesterification process of PDMS with diphenyl carbonate (DPC) and its copolymerization products with bisphenol-A (BPA) for different chain lengths of PDMS. [...] Read more.

This study aimed to improve polydimethylsiloxane (PDMS) conversion in the preparation of polycarbonate (PC)–polydimethylsiloxane (PDMS) copolymer through melt polycondensation. We examined the transesterification process of PDMS with diphenyl carbonate (DPC) and its copolymerization products with bisphenol-A (BPA) for different chain lengths of PDMS. The key factors affecting PDMS conversion were investigated. Results showed that long-chain PDMS required a higher critical transesterification level (38.6%) to improve miscibility with DPC. During polycondensation, side reactions were more prone to occur when the equilibrium transesterification level of long-chain PDMS was lower. PDMS conversion was also lower when more short-chain PDMS was fed. Increasing the chain length of PDMS also reduced PDMS conversion. Notably, increasing the amount of KOH can significantly improve PDMS conversion throughout the polycondensation stage by increasing the equilibrium transesterification level of long-chain PDMS, thereby inhibiting the occurrence of side reactions. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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19 pages, 38129 KiB

Open AccessArticle

Facile Synthesis of Thermoplastic Polyamide Elastomers Based on Amorphous Polyetheramine with Damping Performance

by Jie Jiang, Qiuyu Tang, Xun Pan, Jinjin Li, Ling Zhao, Zhenhao Xi and Weikang Yuan

Polymers 2021, 13(16), 2645; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13162645 - 09 Aug 2021

Cited by 6 | Viewed by 3633

Abstract

Novel thermoplastic polyamide elastomers (TPAEs) consisting of long-chain semicrystalline polyamide 1212 (PA1212) and amorphous polyetheramine were synthesized via one-pot melt polycondensation. The method provides accessible routes to prepare TPAEs with a high tolerance of compatibility between polyamide and polyether oligomers compared with the [...] Read more.

Novel thermoplastic polyamide elastomers (TPAEs) consisting of long-chain semicrystalline polyamide 1212 (PA1212) and amorphous polyetheramine were synthesized via one-pot melt polycondensation. The method provides accessible routes to prepare TPAEs with a high tolerance of compatibility between polyamide and polyether oligomers compared with the traditional two-step method. These TPAEs with 10 wt % to 76 wt % of soft content were obtained by reaction of dodecanedioic acid, 1,12-dodecanediamine, and poly(propylene glycol) (PPG) diamine. The structure–property relationships of TPAEs were systematically studied. The chemical structure and the morphologic analyses have revealed that microphase separation occurs in the amorphous region. The TPAEs that have long-chain PPG segments consist of a crystalline polyamide domain, amorphous polyamide-rich domain, and amorphous polyetheramine-rich domain, while the ones containing short-chain PPG segments comprise of a crystalline polyamide domain and miscible amorphous polyamide phase and amorphous polyetheramine phase due to the compatibility between short-chain polyetheramine and amorphous polyamide. These novel TPAEs show good damping performance at low temperature, especially the TPAEs that incorporated 76 wt % and 62 wt % of PPG diamine. The TPAEs exhibit high elastic properties and low residual strain at room temperature. They are lightweight with density between 1.01 and 1.03 g/cm³. The long-chain TPAEs have well-balanced properties of low density, high elastic return, and high shock-absorbing ability. This work provides a route to expand TPAEs to damping materials with special application for sports equipment used in extremely cold conditions such as ski boots. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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15 pages, 2928 KiB

Open AccessArticle

Novel Chemical Architectures Based on Beta-Cyclodextrin Derivatives Covalently Attached on Polymer Spheres

by Stefan Bucur, Ionel Mangalagiu, Aurel Diacon, Alexandra Mocanu, Florica Rizea, Raluca Somoghi, Adi Ghebaur, Aurelian Cristian Boscornea and Edina Rusen

Polymers 2021, 13(14), 2338; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13142338 - 16 Jul 2021

Cited by 3 | Viewed by 2393

Abstract

This study presents the synthesis and characterization of polymer derivatives of beta-cyclodextrin (BCD), obtained by chemical grafting onto spherical polymer particles (200 nm) presenting oxirane functional groups at their surface. The polymer spheres were synthesized by emulsion polymerization of styrene (ST) and hydroxyethyl [...] Read more.

This study presents the synthesis and characterization of polymer derivatives of beta-cyclodextrin (BCD), obtained by chemical grafting onto spherical polymer particles (200 nm) presenting oxirane functional groups at their surface. The polymer spheres were synthesized by emulsion polymerization of styrene (ST) and hydroxyethyl methacrylate (HEMA), followed by the grafting on the surface of glycidyl methacrylate (GMA) by seeded emulsion polymerization. The BCD-polymer derivatives were obtained using two BCD derivatives with hydroxylic (BCD-OH) and amino groups (BCD-NH₂). The degree of polymer covalent functionalization using the BCD-OH and BCD-NH₂ derivatives were determined to be 4.27 and 19.19 weight %, respectively. The adsorption properties of the materials were evaluated using bisphenol A as a target molecule. The best fit for the adsorption kinetics was Lagergren’s model (both for Q_e value and for R²) together with Weber’s intraparticle diffusion model in the case of ST-HEMA-GMA-BCD-NH₂. The isothermal adsorption evaluation indicated that both systems follow a Langmuir type behavior and afforded a Q_max value of 148.37 mg g⁻¹ and 37.09 mg g⁻¹ for ST-HEMA-GMA-BCD-NH₂ and ST-HEMA-GMA-BCD-OH, respectively. The BCD-modified polymers display a degradation temperature of over 400 °C which can be attributed to the existence of hydrogen bonds and BCD thermal degradation pathway in the presence of the polymers. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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18 pages, 5270 KiB

Open AccessArticle

The Effect of Titanium Tetra-Butoxide Catalyst on the Olefin Polymerization

by Mohammed S. Alsuhybani and Eid M. Alosime

Polymers 2021, 13(13), 2109; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13132109 - 26 Jun 2021

Cited by 1 | Viewed by 2645

Abstract

The purpose of this study was to assess the ability of titanium Ti(IV) alkyloxy compounds supported by organic polymer polyvinyl chloride (PVC) to polymerize ethylene by feeding triethylaluminium (TEA) as a cocatalyst. Additionally, the impacts of the molar ratio of [Al]/[Ti] on the [...] Read more.

The purpose of this study was to assess the ability of titanium Ti(IV) alkyloxy compounds supported by organic polymer polyvinyl chloride (PVC) to polymerize ethylene by feeding triethylaluminium (TEA) as a cocatalyst. Additionally, the impacts of the molar ratio of [Al]/[Ti] on the catalytic activities in ethylene’s polymerization and of the comonomer through utilization of diverse quantities of comonomers on a similar or identical activity were studied. The optimal molar ratio of [Al]/[Ti] was 773:1, and the prepared catalyst had an initial activity of up to 2.3 kg PE/mol Ti. h. when the copolymer was incorporated with 64 mmol of 1-octene. The average molecular weight (M_w) of the copolymer produced with the catalysts was between 97 kg/mol and 326 kg/mol. A significant decrease in the M_w was observed, and PDI broadened with increasing concentration of 1-hexene because of the comonomer’s stronger chain transfer capacity. The quick deactivation of titanium butoxide Ti(OBu)₄ on the polymers was found to be associated with increasing oxidation when supported by the catalyst. The presence of Ti(III) after reduction with the aluminum alkyls cleaves the carbon-chlorine bonds of the polymer, producing an inactive polymeric Ti(IV) complex. The results show that synergistic effects play an important role in enhancing the observed rate of reaction, as illustrated by evidence from scanning electron microscopy (SEM). The diffusion of cocatalysts within catalytic precursor particles may also explain the progression of cobweb structures in the polymer particles. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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16 pages, 22025 KiB

Open AccessArticle

A Facile Synthesis Route of Hybrid Polyurea-Polyurethane-MWCNTs Nanocomposite Coatings for Ballistic Protection and Experimental Testing in Dynamic Regime

by Gabriela Toader, Aurel Diacon, Edina Rusen, Florica Rizea, Mircea Teodorescu, Paul O. Stanescu, Celina Damian, Adrian Rotariu, Eugen Trana, Florina Bucur and Raluca Ginghina

Polymers 2021, 13(10), 1618; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13101618 - 17 May 2021

Cited by 10 | Viewed by 2452

Abstract

This study describes a simple, practical, inexpensive, improved, and efficient novel method for obtaining polyurea-polyurethane-multiwall carbon nanotubes (MWCNTs) nanocomposites with enhanced mechanical properties, and their experimental testing in a dynamic regime. SEM and micro-CT investigations validated the homogeneity of the nanocomposite films and [...] Read more.

This study describes a simple, practical, inexpensive, improved, and efficient novel method for obtaining polyurea-polyurethane-multiwall carbon nanotubes (MWCNTs) nanocomposites with enhanced mechanical properties, and their experimental testing in a dynamic regime. SEM and micro-CT investigations validated the homogeneity of the nanocomposite films and uniform dispersion of the nanofiller inside the polymeric matrix. The experimental measurements (TGA, DSC, DMA, and tensile tests) revealed improved thermal and mechanical properties of these new materials. To demonstrate that these nanocomposites are suitable for ballistic protection, impact tests were performed on aluminum plates coated with the polyurea-polyurethane MWCNTs nanocomposites, using a Hopkinson bar set-up. The experimental testing in the dynamic regime of the polyurea- polyurethane-coated aluminum plates confirmed that the nanocomposite layers allow the metal plate to maintain its integrity at a maximum force value that is almost 200% higher than for the uncoated metallic specimens. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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14 pages, 3116 KiB

Open AccessArticle

Kaolin-Enhanced Superabsorbent Composites: Synthesis, Characterization and Swelling Behaviors

by Mengna Chen, Xuelong Chen, Caiyan Zhang, Baozheng Cui, Zewen Li, Dongyu Zhao and Zhe Wang

Polymers 2021, 13(8), 1204; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13081204 - 08 Apr 2021

Cited by 27 | Viewed by 2895

Abstract

One type of low-cost and eco-friendly organic‒inorganic superabsorbent composite (SAPC) was synthesized by free radical polymerization of acrylic acid (AA), starch (ST), sodium alginate (SA) and kaolin (KL) in aqueous solution. The structure and morphology of the SAPC were characterized by Fourier transform [...] Read more.

One type of low-cost and eco-friendly organic‒inorganic superabsorbent composite (SAPC) was synthesized by free radical polymerization of acrylic acid (AA), starch (ST), sodium alginate (SA) and kaolin (KL) in aqueous solution. The structure and morphology of the SAPC were characterized by Fourier transform infrared spectrometer (FT-IR), scanning electron microscope (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The influence of different reaction conditions on water absorption of SAPC, i.e., SA and KL contents, AA neutralization degree (ND), potassium persulfate (KPS) and N, N′-methylenebisacrylamide (MBA) loading were systematically studied. Under the optimal synthesis conditions, very high water absorption of 1200 g/g was achieved. The swelling kinetic mechanism of SAPC was studied by pseudo-second order swelling kinetics model and Ritger‒Peppas model. The performances of SAPC under different environments were tested and results revealed that this new SAPC had excellent swelling capacity, high water retention, good salt tolerance in monovalent salt solution (NaCl solution) and good pH tolerance between 4 and 10. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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13 pages, 10912 KiB

Open AccessArticle

Photophysical, Thermal and Structural Properties of Thiophene and Benzodithiophene-Based Copolymers Synthesized by Direct Arylation Polycondensation Method

by Newayemedhin A. Tegegne, Zelalem Abdissa and Wendimagegn Mammo

Polymers 2021, 13(7), 1151; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13071151 - 04 Apr 2021

Cited by 7 | Viewed by 1976

Abstract

Three low-band-gap copolymers based on isoindigo acceptor units were designed and successfully synthesized by direct arylation polycondensation method. Two of them were benzodithiophene (BDT)-isoindigo copolymers (PBDTI-OD and PBDTI-DT) with 2-octlydodecyl (OD) and 2-decyltetradecyl (DT) substituted isoindigo units, respectively. Thiophene donor and [...] Read more.

Three low-band-gap copolymers based on isoindigo acceptor units were designed and successfully synthesized by direct arylation polycondensation method. Two of them were benzodithiophene (BDT)-isoindigo copolymers (PBDTI-OD and PBDTI-DT) with 2-octlydodecyl (OD) and 2-decyltetradecyl (DT) substituted isoindigo units, respectively. Thiophene donor and DT-substituted isoindigo acceptor units were copolymerized to synthesize PTI-DT. The copolymers have a broad absorption range that extends to over 760 nm with a band gap ≈1.5 eV. The photophysical property studies showed that the BDT-based copolymers have non-polar ground states. Their emission exhibited the population of the intramolecular charge transfer (ICT) state in polar solvents and tightly bound excitonic state in non-polar solvents due to self-aggregation. On the contrary, the emission from the thiophene-based copolymers was only from the tightly bound excitonic state. The thermal decomposition temperature of the copolymers was above 380 °C. The X-ray diffraction pattern of the three copolymers showed a halo due to

π - π

stacking. A second, sharper peak was observed in the BDT-based copolymer with a longer side chain on the isoindigo unit (PBDTI-DT), and the thiophene-based copolymers with PTI-DT, exhibiting a better structural order. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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23 pages, 5758 KiB

Open AccessReview

Facile Synthesis of Novel Disperse Dyes for Dyeing Polyester Fabrics: Demonstrating Their Potential Biological Activities

by Alya M. Al-Etaibi and Morsy Ahmed El-Apasery

Polymers 2022, 14(19), 3966; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14193966 - 22 Sep 2022

Cited by 4 | Viewed by 1873

Abstract

Original work showed the composition of the dyes and the antimicrobial/UV protective properties of a series of dyes obtained in our laboratories over the past twelve years in an easy way using microwave technology and their comparisons with conventional methods. The results we [...] Read more.

Original work showed the composition of the dyes and the antimicrobial/UV protective properties of a series of dyes obtained in our laboratories over the past twelve years in an easy way using microwave technology and their comparisons with conventional methods. The results we obtained clearly indicated that by using the microwave strategy, we were able to synthesize the new disperse dyes in minutes and with a much higher productivity when compared to the traditional methods, which took a much longer time, sometimes up to hours. We also introduced ultrasonic technology in dyeing polyester fabrics at 80 °C for an environmentally friendly approach, which was an alternative to traditional dyeing methods at 100 °C; we obtained a much higher color depth than traditional dyeing methods reaching 102.9%. We presented both the biological activity of the prepared new dyes and the fastness properties and clearly indicated that these dyes possess biological activity and high fastness properties.We presented through the results that when dyeing polyester fabrics with some selected disperse dyes, the color strength of polyester fabrics dyed at high temperatures was greater than the color strength of polyester fabrics dyed at low temperatures by 144%, 186%, 265% and 309%. Finally, we presented that a ZnO or TiO₂ NPs post-dyeing treatment of polyester fabrics is promising strategy for producing polyester fabrics possess multifunction like self-cleaning property, high light fastness, antimicrobial and anti-ultraviolet properties. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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21 pages, 17092 KiB

Open AccessReview

Development of Synthesis and Application of High Molecular Weight Poly(Methyl Methacrylate)

by Ming Yuan, Dayun Huang and Yixuan Zhao

Polymers 2022, 14(13), 2632; https://0-doi-org.brum.beds.ac.uk/10.3390/polym14132632 - 28 Jun 2022

Cited by 12 | Viewed by 8367

Abstract

Poly(methyl methacrylate) (PMMA) is widely used in aviation, architecture, medical treatment, optical instruments and other fields because of its good transparency, chemical stability and electrical insulation. However, the application of PMMA largely depends on its physical properties. Mechanical properties such as tensile strength, [...] Read more.

Poly(methyl methacrylate) (PMMA) is widely used in aviation, architecture, medical treatment, optical instruments and other fields because of its good transparency, chemical stability and electrical insulation. However, the application of PMMA largely depends on its physical properties. Mechanical properties such as tensile strength, fracture surface energy, shear modulus and Young’s modulus are increased with the increase in molecular weight. Consequently, it is of great significance to synthesize high molecular weight PMMA. In this article, we review the application of conventional free radical polymerization, atom transfer radical polymerization (ATRP) and coordination polymerization for preparing high molecular weight PMMA. The mechanisms of these polymerizations are discussed. In addition, applications of PMMA are also summarized. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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27 pages, 4761 KiB

Open AccessReview

Copolymerization of Ethylene with Selected Vinyl Monomers Catalyzed by Group 4 Metal and Vanadium Complexes with Multidentate Ligands: A Short Review

by Marzena Białek and Julia Fryga

Polymers 2021, 13(24), 4456; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13244456 - 19 Dec 2021

Cited by 5 | Viewed by 3971

Abstract

This paper gives a short overview of homogeneous post-metallocene catalysts based on group 4 metal and vanadium complexes bearing multidentate ligands. It summarizes the catalytic behavior of those catalysts in copolymerization of ethylene with 1-olefins, with styrenic monomers and with α,ω-alkenols. The review [...] Read more.

This paper gives a short overview of homogeneous post-metallocene catalysts based on group 4 metal and vanadium complexes bearing multidentate ligands. It summarizes the catalytic behavior of those catalysts in copolymerization of ethylene with 1-olefins, with styrenic monomers and with α,ω-alkenols. The review is focused on finding correlations between the structure of a complex, its catalyst activity and comonomer incorporation ability, as well as the microstructure of the copolymer chains. Full article

(This article belongs to the Special Issue Polymers Synthesis and Characterization)

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