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Advanced Polymer Composite Materials III

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A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Materials Science".

Deadline for manuscript submissions: closed (15 June 2022) | Viewed by 31295

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Prof. Dr. Xiao Hu

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Department of Physics and Astronomy, College of Science and Mathematics, Rowan University, Glassboro, NJ 08028, USA
Interests: polymer; biomaterials; biomacromolecules; regenerative medicine; drug delivery; nanotechnology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue is a continuation of our previous Special Issue on “Advanced Polymer Composite Materials” and "Advanced Polymer Composite Materials II".

A polymer composite is a material system composed of two or more macro/micro/nanoconstituents of different shapes, properties or chemical compositions, at least one of which is a polymer. The design of multifunctional and tunable polymer-based composite materials is an emerging area of research with a wide range of applications in the aerospace industry, the automotive industry, the home appliance industry, the sporting goods industry, as well as the booming biomedical device/biomaterial industry. Polymer composite materials can be classified according to matrix materials (synthetic polymers, biopolymers, inorganic and organic fillers, etc.) and reinforcement geometries (particles, fibers, gels, films, layers, foams, mixtures, etc.). In addition, polymer composites can be a multiphase material with a significant proportion of each phase or a blended material system with a continuous phase that greatly enhances the physical, chemical or biological properties of the material matrix. By optimizing molecular interfaces between different components, polymer-based composite materials can also encompass a range of functions, such as thermal stability at different temperatures, elasticity to support diverse structures, electrical sensitivity in variable sensors, and optical properties for advanced fiberglass technology. In this Special Issue, we will highlight the latest developments in these advanced polymer composite materials, including their design, synthesis, characterization, manufacturing, and modeling, as well as their various applications. Both research and review articles are welcome.

Dr. Xiao Hu
Guest Editor

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Keywords

composite materials
polymer and biopolymer
physical and chemical properties
composite design, characterization, structure, and function

Published Papers (10 papers)

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Research

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17 pages, 3630 KiB

Open AccessArticle

Fully Symmetric Cyclodextrin Polycarboxylates: How to Determine Reliable Protonation Constants from NMR Titration Data

by Eszter Kalydi, Milo Malanga, Dóra Ujj, Gábor Benkovics, Zoltán Szakács and Szabolcs Béni

Int. J. Mol. Sci. 2022, 23(22), 14448; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms232214448 - 21 Nov 2022

Cited by 4 | Viewed by 1953

Abstract

Acid-base properties of cyclodextrins (CDs), persubstituted at C-6 by 3-mercaptopropionic acid, sualphadex (Suα-CD), subetadex (Suβ-CD) and sugammadex (Suγ-CD, the antidote of neuromuscular blocking steroids) were studied by ¹H NMR-pH titrations. For each CD, the severe overlap in protonation steps prevented the calculation of macroscopic pK_a values using the standard data fitting model. Considering the full symmetry of polycarboxylate structures, we reduced the number of unknown NMR parameters in the “Q-fitting” or the novel “equidistant macroscopic” evaluation approaches. These models already provided pK_a values, but some of them proved to be physically unrealistic, deceptively suggesting cooperativity in carboxylate protonations. The latter problem could be circumvented by adapting the microscopic site-binding (cluster expansion) model by Borkovec, which applies pairwise interactivity parameters to quantify the mutual basicity-decreasing effect of carboxylate protonations. Surprisingly, only a single averaged interactivity parameter could be calculated reliably besides the carboxylate ‘core’ microconstant for each CD derivative. The speciation of protonation isomers hence could not be resolved, but the optimized microscopic basicity parameters could be converted to the following sets of macroscopic pK_a values: 3.84, 4.35, 4.81, 5.31, 5.78, 6.28 for Suα-CD; 3.82, 4.31, 4.73, 5.18, 5.64, 6.06, 6.54 for Suβ-CD and 3.83, 4.28, 4.65, 5.03, 5.43, 5.81, 6.18, 6.64 for Suγ-CD. The pH-dependent charge of these compounds can now be accurately calculated, in support of designing new analytical methods to exploit their charge-dependent molecular recognition such as in cyclodextrin-aided chiral capillary electrophoresis. Full article

(This article belongs to the Special Issue Advanced Polymer Composite Materials III)

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23 pages, 6618 KiB

Open AccessArticle

Tailoring Nylon 6/Acrylonitrile-Butadiene-Styrene Nanocomposites for Application against Electromagnetic Interference: Evaluation of the Mechanical, Thermal and Electrical Behavior, and the Electromagnetic Shielding Efficiency

by Carlos Bruno Barreto Luna, Emanuel Pereira do Nascimento, Danilo Diniz Siqueira, Bluma Guenther Soares, Pankaj Agrawal, Tomás Jeferson Alves de Mélo and Edcleide Maria Araújo

Int. J. Mol. Sci. 2022, 23(16), 9020; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms23169020 - 12 Aug 2022

Cited by 7 | Viewed by 1831

Abstract

Nylon 6/acrylonitrile-butadiene-styrene nanocomposites were prepared by mixing in a molten state and injection molded for application in electromagnetic interference shielding and antistatic packaging. Multi-wall carbon nanotubes (MWCNT) and maleic anhydride-grafted ABS compatibilizer were incorporated to improve the electrical conductivity and mechanical performance. The nanocomposites were characterized by oscillatory rheology, Izod impact strength, tensile strength, thermogravimetry, current-voltage measurements, shielding against electromagnetic interference, and scanning electron microscopy. The rheological behavior evidenced a severe increase in complex viscosity and storage modulus, which suggests an electrical percolation phenomenon. Adding 1 to 5 phr MWCNT into the nanocomposites produced electrical conductivities between 1.22 × 10⁻⁶ S/cm and 6.61 × 10⁻⁵ S/cm. The results make them suitable for antistatic purposes. The nanocomposite with 5 phr MWCNT showed the highest electromagnetic shielding efficiency, with a peak of –10.5 dB at 9 GHz and a value around –8.2 dB between 11 and 12 GHz. This was possibly due to the higher electrical conductivity of the 5 phr MWCNT composition. In addition, the developed nanocomposites, regardless of MWCNT content, showed tenacious behavior at room temperature. The results reveal the possibility for tailoring the properties of insulating materials for application in electrical and electromagnetic shielding. Additionally, the good mechanical and thermal properties further widen the application range. Full article

(This article belongs to the Special Issue Advanced Polymer Composite Materials III)

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14 pages, 5770 KiB

Open AccessCommunication

Controlling Gas Generation of Li-Ion Battery through Divinyl Sulfone Electrolyte Additive

by Woon Ih Choi, Insun Park, Jae Sik An, Dong Young Kim, Meiten Koh, Inkook Jang, Dae Sin Kim, Yoon-Sok Kang and Youngseon Shim

Int. J. Mol. Sci. 2022, 23(13), 7328; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms23137328 - 30 Jun 2022

Cited by 1 | Viewed by 2064

Abstract

The focus of mainstream lithium-ion battery (LIB) research is on increasing the battery’s capacity and performance; however, more effort should be invested in LIB safety for widespread use. One aspect of major concern for LIB cells is the gas generation phenomenon. Following conventional battery engineering practices with electrolyte additives, we examined the potential usage of electrolyte additives to address this specific issue and found a feasible candidate in divinyl sulfone (DVSF). We manufactured four identical battery cells and employed an electrolyte mixture with four different DVSF concentrations (0%, 0.5%, 1.0%, and 2.0%). By measuring the generated gas volume from each battery cell, we demonstrated the potential of DVSF additives as an effective approach for reducing the gas generation in LIB cells. We found that a DVSF concentration of only 1% was necessary to reduce the gas generation by approximately 50% while simultaneously experiencing a negligible impact on the cycle life. To better understand this effect on a molecular level, we examined possible electrochemical reactions through ab initio molecular dynamics (AIMD) based on the density functional theory (DFT). From the electrolyte mixture’s exposure to either an electrochemically reductive or an oxidative environment, we determined the reaction pathways for the generation of CO₂ gas and the mechanism by which DVSF additives effectively blocked the gas’s generation. The key reaction was merging DVSF with cyclic carbonates, such as FEC. Therefore, we concluded that DVSF additives could offer a relatively simplistic and effective approach for controlling the gas generation in lithium-ion batteries. Full article

(This article belongs to the Special Issue Advanced Polymer Composite Materials III)

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17 pages, 4090 KiB

Open AccessArticle

Fabrication of CL-20/HMX Cocrystal@Melamine–Formaldehyde Resin Core–Shell Composites Featuring Enhanced Thermal and Safety Performance via In Situ Polymerization

by Binghui Duan, Xianming Lu, Hongchang Mo, Bojun Tan, Bozhou Wang and Ning Liu

Int. J. Mol. Sci. 2022, 23(12), 6710; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms23126710 - 16 Jun 2022

Cited by 11 | Viewed by 1536

Abstract

Safety concerns remain a bottleneck for the application of 2,4,6,8,10,12-hexanitro- 2,4,6,8,10,12-hexaazaisowurtzitane (CL-20)/1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX) cocrystal. Melamine–formaldehyde (MF) resin was chosen to fabricate CL-20/HMX cocrystal-based core–shell composites (CH@MF composites) via a facile in situ polymerization method. The resulted CH@MF composites were comprehensively characterized, and a compact core–shell structure was confirmed. The effects of the shell content on the properties of the composites were explored as well. As a result, we found that, except for CH@MF–2 with a 1% shell content, the increase in shell content led to a rougher surface morphology and more close-packed structure. The thermal decomposition peak temperature improved by 5.3 °C for the cocrystal enabled in 1.0 wt% MF resin. Regarding the sensitivity, the CH@MF composites exhibited a significantly reduced impact and friction sensitivity with negligible energy loss compared with the raw cocrystal and physical mixtures due to the cushioning and insulation effects of the MF coating. The formation mechanism of the core–shell micro-composites was further clarified. Overall, this work provides a green, facile and industrially potential strategy for the desensitization of energetic cocrystals. The CH@MF composites with high thermal stability and low sensitivity are promising to be applied in propellants and polymer-bonded explosive (PBX) formulations. Full article

(This article belongs to the Special Issue Advanced Polymer Composite Materials III)

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15 pages, 3746 KiB

Open AccessArticle

Bio-Based Rigid Polyurethane Foam Composites Reinforced with Bleached Curauá Fiber

by Sylwia Członka, Eduardo Fischer Kerche, Roberta Motta Neves, Anna Strąkowska and Krzysztof Strzelec

Int. J. Mol. Sci. 2021, 22(20), 11203; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms222011203 - 18 Oct 2021

Cited by 13 | Viewed by 2123

Abstract

This study aims to evaluate the influence of using a bleached Curauá fiber (CF) as filler in a novel rigid polyurethane foam (RPUF) composite. The influence of 0.1, 0.5 and 1 wt.% of the reinforcements on the processing characteristics, cellular structure, mechanical, dynamic-mechanical, thermal, and flame behaviors were assessed and discussed for RPUF freely expanded. The results showed that the use of 0.5 wt.% of CF resulted in RPUF with smoother cell structure with low differences on the processing times and viscosity for the filled pre-polyol. These morphological features were responsible for the gains in mechanical properties, in both parallel and perpendicular rise directions, and better viscoelastic characteristics. Despite the gains, higher thermal conductivity and lower flammability were reported for the developed RPUF composites, related to the high content of cellulose and hemicellulose on the bleached CF chemical composition. This work shows the possibility of using a Brazilian vegetable fiber, with low exploration for the manufacturing of composite materials with improved properties. The developed RPUF presents high applicability as enhanced cores for the manufacturing of structural sandwich panels, mainly used in civil, aircraft, and marine industries. Full article

(This article belongs to the Special Issue Advanced Polymer Composite Materials III)

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15 pages, 4499 KiB

Open AccessArticle

Aging Resistance of Biocomposites Crosslinked with Silica and Quercetin

by Anna Masek and Olga Olejnik

Int. J. Mol. Sci. 2021, 22(19), 10894; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms221910894 - 08 Oct 2021

Cited by 7 | Viewed by 1997

Abstract

This research focuses on revealing the double role of quercetin accompanied by silica in epoxidized natural rubber. A crosslinking ability with antioxidative properties exists and reveals the dependence of these functions on quercetin content. Here, the aging resistance of self-healable biocomposites was analyzed. The self-healing properties were presented in our previous work. The stabilizing effect of quercetin applied as a crosslinking agent has been studied in epoxidized natural rubber with a 50 mol% of epoxidation (ENR-50). Some of five -OH moiety groups existing in the quercetin structure are able to react with epoxy rings of ENR-50 and cure this elastomer, whereas other free hydroxyl groups can donate the hydrogen molecule to a radical molecule, stabilizing it. The aging resistance of prepared composites was estimated by mechanical tests conducted before and after different types of aging, as well as by differences in color and surface energy between aged and un-aged samples. Changes within the oxygen function, which occurred as a result of the aging process, were observed using FT-IR absorbance spectroscopy. Furthermore, the impact of quercetin content on composites’ thermal stability was investigated by thermogravimetry (TGA). According to the results, a proper dose of quercetin can act as a crosslinker and antioxidant in ENR-50 at the same time. Full article

(This article belongs to the Special Issue Advanced Polymer Composite Materials III)

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15 pages, 3803 KiB

Open AccessArticle

Vermiculite Filler Modified with Casein, Chitosan, and Potato Protein as a Flame Retardant for Polyurethane Foams

by Karolina Miedzińska, Sylwia Członka, Anna Strąkowska and Krzysztof Strzelec

Int. J. Mol. Sci. 2021, 22(19), 10825; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms221910825 - 06 Oct 2021

Cited by 16 | Viewed by 2485

Abstract

In this study, polyurethane (PU) composite foams were modified with 2 wt.% of vermiculite fillers, which were themselves modified with casein, chitosan, and potato protein. The impact of the fillers on selected properties of the obtained composites, including their rheological (foaming behavior, dynamic viscosity), thermal (temperature of thermal decomposition stages), flame-retardant (e.g., limiting oxygen index, ignition time, heat peak release), and mechanical properties (toughness, compressive strength (parallel and perpendicular), flexural strength) were investigated. Among all the modified polyurethane composites, the greatest improvement was noticed in the PU foams filled with vermiculite modified with casein and chitosan. For example, after the addition of modified vermiculite fillers, the foams’ compressive strength was enhanced by ~6–18%, their flexural strength by ~2–10%, and their toughness by ~1–5%. Most importantly, the polyurethane composites filled with vermiculite filler and modified vermiculite fillers exhibited improved flame resistance characteristics (the value of total smoke release was reduced by ~34%, the value of peak heat release was reduced by ~25%). Full article

(This article belongs to the Special Issue Advanced Polymer Composite Materials III)

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15 pages, 1350 KiB

Open AccessArticle

The Selectivity of Immunoassays and of Biomimetic Binding Assays with Imprinted Polymers

by Gergely Becskereki, George Horvai and Blanka Tóth

Int. J. Mol. Sci. 2021, 22(19), 10552; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms221910552 - 29 Sep 2021

Cited by 1 | Viewed by 1593

Abstract

Molecularly imprinted polymers have been shown to be useful in competitive biomimetic binding assays. Recent developments in materials science have further enhanced the capabilities of imprinted polymers. Binding assays, biological and biomimetic alike, owe their usefulness to their selectivity. The selectivity of competitive binding assays has been characterized with the cross-reactivity, which is usually expressed as the ratio of the measured IC50 concentration values of the interferent and the analyte, respectively. Yet this cross-reactivity is only a rough estimate of analytical selectivity. The relationship between cross-reactivity and analytical selectivity has apparently not been thoroughly investigated. The present work shows that this relationship depends on the underlying model of the competitive binding assay. For the simple but widely adopted model, where analyte and interferent compete for a single kind of binding site, we provide a simple formula for analytical selectivity. For reasons of an apparent mathematical problem, this formula had not been found before. We also show the relationship between analytical selectivity and cross-reactivity. Selectivity is also shown to depend on the directly measured quantity, e.g., the bound fraction of the tracer. For those cases where the one-site competitive model is not valid, a practical procedure is adopted to estimate the analytical selectivity. This procedure is then used to analyze the example of the competitive two-site binding model, which has been the main model for describing molecularly imprinted polymer behavior. The results of this work provide a solid foundation for assay development. Full article

(This article belongs to the Special Issue Advanced Polymer Composite Materials III)

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18 pages, 5787 KiB

Open AccessArticle

Polyurethane Composites Reinforced with Walnut Shell Filler Treated with Perlite, Montmorillonite and Halloysite

by Sylwia Członka, Agnė Kairytė, Karolina Miedzińska and Anna Strąkowska

Int. J. Mol. Sci. 2021, 22(14), 7304; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms22147304 - 07 Jul 2021

Cited by 17 | Viewed by 2581

Abstract

In the following study, polyurethane (PUR) composites were modified with 2 wt.% of walnut shell filler modified with selected mineral compounds–perlite, montmorillonite, and halloysite. The impact of modified walnut shell fillers on selected properties of PUR composites, such as rheological properties (dynamic viscosity, foaming behavior), mechanical properties (compressive strength, flexural strength, impact strength), dynamic-mechanical behavior (glass transition temperature, storage modulus), insulation properties (thermal conductivity), thermal characteristic (temperature of thermal decomposition stages), and flame retardant properties (e.g., ignition time, limiting oxygen index, heat peak release) was investigated. Among all modified types of PUR composites, the greatest improvement was observed for PUR composites filled with walnut shell filler functionalized with halloysite. For example, on the addition of such modified walnut shell filler, the compressive strength was enhanced by ~13%, flexural strength by ~12%, and impact strength by ~14%. Due to the functionalization of walnut shell filler with thermally stable flame retardant compounds, such modified PUR composites were characterized by higher temperatures of thermal decomposition. Most importantly, PUR composites filled with flame retardant compounds exhibited improved flame resistance characteristics-in all cases, the value of peak heat release was reduced by ~12%, while the value of total smoke release was reduced by ~23%. Full article

(This article belongs to the Special Issue Advanced Polymer Composite Materials III)

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Review

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20 pages, 3760 KiB

Open AccessReview

Recent Progress in Biopolymer-Based Hydrogel Materials for Biomedical Applications

by Ayaz Mahmood, Dev Patel, Brandon Hickson, John DesRochers and Xiao Hu

Int. J. Mol. Sci. 2022, 23(3), 1415; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms23031415 - 26 Jan 2022

Cited by 83 | Viewed by 10956

Abstract

Hydrogels from biopolymers are readily synthesized, can possess various characteristics for different applications, and have been widely used in biomedicine to help with patient treatments and outcomes. Polysaccharides, polypeptides, and nucleic acids can be produced into hydrogels, each for unique purposes depending on their qualities. Examples of polypeptide hydrogels include collagen, gelatin, and elastin, and polysaccharide hydrogels include alginate, cellulose, and glycosaminoglycan. Many different theories have been formulated to research hydrogels, which include Flory-Rehner theory, Rubber Elasticity Theory, and the calculation of porosity and pore size. All these theories take into consideration enthalpy, entropy, and other thermodynamic variables so that the structure and pore sizes of hydrogels can be formulated. Hydrogels can be fabricated in a straightforward process using a homogeneous mixture of different chemicals, depending on the intended purpose of the gel. Different types of hydrogels exist which include pH-sensitive gels, thermogels, electro-sensitive gels, and light-sensitive gels and each has its unique biomedical applications including structural capabilities, regenerative repair, or drug delivery. Major biopolymer-based hydrogels used for cell delivery include encapsulated skeletal muscle cells, osteochondral muscle cells, and stem cells being delivered to desired locations for tissue regeneration. Some examples of hydrogels used for drug and biomolecule delivery include insulin encapsulated hydrogels and hydrogels that encompass cancer drugs for desired controlled release. This review summarizes these newly developed biopolymer-based hydrogel materials that have been mainly made since 2015 and have shown to work and present more avenues for advanced medical applications. Full article

(This article belongs to the Special Issue Advanced Polymer Composite Materials III)

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