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Feature Paper in Section Materials Chemistry

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Materials Chemistry".

Deadline for manuscript submissions: closed (20 August 2022) | Viewed by 24418

Special Issue Editor

Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń, Poland
Interests: polymers; biopolymers and copolymers; polymer blends and (nano)composites; polymer characterization; polymer photochemistry; photopolymerization; biodegradable and bioactive polymers; thermal and photochemical degradation; piezoelectric polymers; biomedical; pharmaceutical and cosmetics application of polymers
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Special Issue Information

Dear Colleagues,

The subject of this issue covers the broadly understood chemistry of materials, in particular the chemistry of organic and inorganic compounds as well as polymers and biopolymers, their mixtures, and composites. The work may concern chemical synthesis or the production of new materials as a result of the introduction of modifying substances, nano-fillers or compounds with biological, photochemical, or other activity. Works on the characterization of the obtained materials using analytical and instrumental methods, including their physicochemical properties, thermal and photochemical stability, biodegradability, and the possibility of their application in modern technologies (including science, industry, and medicine) will be taken into account. Both extensive reviews and research work will be especially welcome.

Prof. Dr. Halina Kaczmarek
Guest Editor

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Keywords

  • organic and inorganic compounds
  • polymers and biopolymers
  • composites and nanocomposites
  • synthesis
  • modification
  • characterization of properties
  • applications

Published Papers (13 papers)

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Research

12 pages, 3837 KiB  
Article
Genipin-Crosslinked Gelatin/Chitosan-Based Functional Films Incorporated with Rosemary Essential Oil and Quercetin
by Swarup Roy and Jong-Whan Rhim
Materials 2022, 15(11), 3769; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15113769 - 25 May 2022
Cited by 30 | Viewed by 2801
Abstract
Functional food packaging films were prepared using a binary mixture of chitosan and gelatin through crosslinking with genipin and hybridization with rosemary essential oil and quercetin. The mixture of chitosan and gelatin produced the compatible film, and the added fillers also showed good [...] Read more.
Functional food packaging films were prepared using a binary mixture of chitosan and gelatin through crosslinking with genipin and hybridization with rosemary essential oil and quercetin. The mixture of chitosan and gelatin produced the compatible film, and the added fillers also showed good compatibility. The physical properties of the chitosan/gelatin film were not greatly affected by crosslinking with genipin, and the functionality of the composite film was increased by the addition of rosemary essential oil and quercetin. The bioactive additives did not significantly affect the hydrophobicity and water vapor barrier properties of the chitosan/gelatin film but significantly changed the color, while the mechanical and thermal properties were slightly affected. The addition of these functional fillers significantly improved the UV protection, antioxidant, and antibacterial properties of the chitosan/gelatin film. Therefore, the novel chitosan/gelatin film with genipin crosslinking and the integration of rosemary essential oil and quercetin is considered to have high potential for applications in active food packaging. Full article
(This article belongs to the Special Issue Feature Paper in Section Materials Chemistry)
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15 pages, 3136 KiB  
Article
Thermal Stability of Fluorescent Chitosan Modified with Heterocyclic Aromatic Dyes
by Dagmara Bajer and Halina Kaczmarek
Materials 2022, 15(10), 3667; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15103667 - 20 May 2022
Cited by 2 | Viewed by 1295
Abstract
Fluorescent biopolymer derivatives are increasingly used in biology and medicine, but their resistance to heat and UV radiation, which are sterilizing agents, is relatively unknown. In this work, chitosan (CS) modified by three different heterocyclic aromatic dyes based on benzimidazole, benzothiazole, and benzoxazole [...] Read more.
Fluorescent biopolymer derivatives are increasingly used in biology and medicine, but their resistance to heat and UV radiation, which are sterilizing agents, is relatively unknown. In this work, chitosan (CS) modified by three different heterocyclic aromatic dyes based on benzimidazole, benzothiazole, and benzoxazole (assigned as IBm, BTh, and BOx) has been studied. The thermal properties of these CS derivatives have been determined using the Thermogravimetric Analysis coupled with the Fourier Transform Infrared spectroscopy of volatile degradation products. The influence of UV radiation on the thermal resistance of modified, fluorescent chitosan samples was also investigated. Based on the temperature onset as well as the decomposition temperatures at a maximal rate, IBm was found to be more thermally stable than BOx and BTh. However, this dye gave off the most volatile products (mainly water, ammonia, carbon oxides, and carbonyl/ether compounds). The substitution of dyes for chitosan changes its thermal stability slightly. Characteristic decomposition temperatures in modified CS vary by a few degrees (<10 °C) from the virgin sample. Considering the temperatures of the main decomposition stage, CS-BOx turned out to be the most stable. The UV irradiation of chitosan derivatives leads to minor changes in the thermal parameters and a decrease in the number of volatile degradation products. It was concluded that the obtained CS derivatives are characterized by good resistance to heat and UV irradiation, which extends the possibilities of using these innovative materials. Full article
(This article belongs to the Special Issue Feature Paper in Section Materials Chemistry)
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21 pages, 4423 KiB  
Article
The Use of Chitosan and Starch-Based Flocculants for Filter Backwash Water Treatment
by Piotr Maćczak, Halina Kaczmarek, Marta Ziegler-Borowska, Katarzyna Węgrzynowska-Drzymalska and Aleksandra Burkowska-But
Materials 2022, 15(3), 1056; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15031056 - 29 Jan 2022
Cited by 20 | Viewed by 2827
Abstract
Inorganic aluminum or iron salts supported with synthetic polymers are commonly used to eradicate colloidal particles from water in coagulation and flocculation processes. Nevertheless, these agents have several disadvantages, such as large volumes of sludge produced or environmental toxicity. Recently biodegradable polymers have [...] Read more.
Inorganic aluminum or iron salts supported with synthetic polymers are commonly used to eradicate colloidal particles from water in coagulation and flocculation processes. Nevertheless, these agents have several disadvantages, such as large volumes of sludge produced or environmental toxicity. Recently biodegradable polymers have been suggested as eco-friendly flocculants for water treatment. This study aimed to investigate the possibilities of using starch and chitosan and their oxidized derivatives as flocculants for filter backwash water treatment. Dialdehyde starch (DST) and dialdehyde chitosan (DCT) were synthesized by periodate oxidization of natural starch from corn and low molecular weight chitosan. The obtained materials have been characterized with scanning electron microscopy (SEM), ATR-FTIR spectroscopy, and thermogravimetric analysis (TGA). Furthermore, we studied the flocculation properties of polysaccharide flocculants in a series of jar tests. The effectiveness of chitosan and starched-based flocculants was compared to synthetic polymers commonly used to treat iron ions-rich filter backwash water. The environmental aspects of these chemicals, particularly the biodegradability of post-flocculation residues, were also addressed. It was found that oxidized starch and chitosan derivatives can be used as ecological flocculating materials to treat potable water or sludge. Full article
(This article belongs to the Special Issue Feature Paper in Section Materials Chemistry)
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16 pages, 2716 KiB  
Article
Overcoming Antibiotic Resistance: Playing the ‘Silver Nanobullet’ Card
by Morena Nocchetti, Elisa Boccalon, Monica Pica, Nicoletta Maria Rosaria Giordano, Francesco Finori, Donatella Pietrella and Antonio Cipiciani
Materials 2022, 15(3), 932; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15030932 - 26 Jan 2022
Cited by 1 | Viewed by 1361
Abstract
Enhancing the antibacterial activity of old antibiotics by a multitarget approach, such as combining antibiotics with metal nanoparticles, is a valuable strategy to overcome antibacterial resistance. In this work, the synergistic antimicrobial effect of silver nanoparticles and antibiotics, immobilized on a solid support, [...] Read more.
Enhancing the antibacterial activity of old antibiotics by a multitarget approach, such as combining antibiotics with metal nanoparticles, is a valuable strategy to overcome antibacterial resistance. In this work, the synergistic antimicrobial effect of silver nanoparticles and antibiotics, immobilized on a solid support, was investigated. Nanometric layered double hydroxides (LDH) based on Zn(II) and Al(III) were prepared by the double microemulsion technique. The dual function of LDH as an anionic exchanger and support for metal nanoparticles was exploited to immobilize both silver and antibiotics. Cefazolin (CFZ), a β-lactam, and nalidixic acid (NAL), a quinolone, were selected and intercalated into LDH obtaining ZnAl-CFZ and ZnAl-NAL samples. These samples were used for the growth of silver nanoparticles with dimension ranging from 2.5 to 8 nm. Silver and antibiotics release profiles, from LDH loaded with antibiotics and Ag/antibiotics, were evaluated in two different media: water and phosphate buffer. Interestingly, the release profiles are affected by both the acceptor media and the presence of silver. The synergistic antibacterial activity of LDH containing both silver and antibiotics were investigated on gram-positives (Staphylococcus aureus and Streptococcus pneumoniae) and gram-negatives (Pseudomonas aeruginosa) and compared with the plain antimicrobials and LDH containing only antibiotics or silver. Full article
(This article belongs to the Special Issue Feature Paper in Section Materials Chemistry)
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14 pages, 3257 KiB  
Article
1D-Zigzag Eu3+/Tb3+ Coordination Chains as Luminescent Ratiometric Thermometers Endowed with Multicolor Emission
by Luca Bellucci, Gregorio Bottaro, Luca Labella, Fabio Marchetti, Simona Samaritani, Daniela Belli Dell'Amico and Lidia Armelao
Materials 2021, 14(21), 6445; https://doi.org/10.3390/ma14216445 - 27 Oct 2021
Cited by 5 | Viewed by 1535
Abstract
Two homometallic Coordination Polymers (CPs) with composition [Ln(hfac)3bipy]n (Ln3+ = Eu3+, 1, and Tb3+, 2; hfac = hexafluoroacetylacetonato, bipy = 4,4′-bipyridine) were used to develop a family of ratiometric luminescent thermometers containing Eu [...] Read more.
Two homometallic Coordination Polymers (CPs) with composition [Ln(hfac)3bipy]n (Ln3+ = Eu3+, 1, and Tb3+, 2; hfac = hexafluoroacetylacetonato, bipy = 4,4′-bipyridine) were used to develop a family of ratiometric luminescent thermometers containing Eu3+ and Tb3+ as red and green emitters, respectively. The thermometric properties of pure CPs and of their mixtures having an Eu3+/Tb3+ molar ratio of 1:1, 1:3, 1:5, and 1:10 (samples: Eu1Tb1, Eu1Tb3, Eu1Tb5, and Eu1Tb10) were studied in the 83–383 K temperature range. Irrespective of the chemical composition, we observed similar thermometric responses characterized by broad applicative temperature ranges (from 100 to 165 K wide), and high relative thermal sensitivity values (Sr), up to 2.40% K−1, in the physiological temperature range (298–318 K). All samples showed emissions endowed with peculiar and continuous color variation from green (83 K) to red (383 K) that can be exploited to develop a colorimetric temperature indicator. At fixed temperature, the color of the emitted light can be tuned by varying composition and excitation wavelength. Full article
(This article belongs to the Special Issue Feature Paper in Section Materials Chemistry)
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14 pages, 1412 KiB  
Article
Phosphorous and Silica Recovery from Rice Husk Poultry Litter Ash: A Sustainability Analysis Using a Zero-Waste Approach
by Laura Fiameni, Ario Fahimi, Claudio Marchesi, Giampiero Pasquale Sorrentino, Alessandra Zanoletti, Karen Moreira, Bruno Valentim, Georgeta Predeanu, Laura Eleonora Depero and Elza Bontempi
Materials 2021, 14(21), 6297; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14216297 - 22 Oct 2021
Cited by 2 | Viewed by 1384
Abstract
Phosphate rocks are a critical resource for the European Union, and alternative sources to assure the future production of a new generation of fertilizers are to be assessed. In this study, a statistical approach, combined with a sustainability evaluation for the recovery of [...] Read more.
Phosphate rocks are a critical resource for the European Union, and alternative sources to assure the future production of a new generation of fertilizers are to be assessed. In this study, a statistical approach, combined with a sustainability evaluation for the recovery of materials from waste containing phosphorus (P), is presented. This work proposes a strategy to recover P and silica (SiO2) from rice husk poultry litter ash (RHPLA). The design of experiment (DoE) method was applied to maximize the P extraction using hydrochloric acid (HCl), with the aim to minimize the contamination that can occur by leachable heavy metals present in RHPLA, such as zinc (Zn). Two independent variables, the molar concentration of the acid, and the liquid-to-solid ratio (L/S) between the acid and RHPLA, were used in the experimental design to optimize the operating parameters. The statistical analysis showed that a HCl concentration of 0.34 mol/L and an L/S ratio of 50 are the best conditions to recover P with low Zn contamination. Concerning the SiO2, its content in RHPLA is too low to consider the proposed recovery process as advantageous. However, based on our analysis, this process should be sustainable to recover SiO2 when its content in the starting materials is more than 80%. Full article
(This article belongs to the Special Issue Feature Paper in Section Materials Chemistry)
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12 pages, 2326 KiB  
Article
Impact of the Graphite Fillers on the Thermal Processing of Graphite/Poly(lactic acid) Composites
by Daniel Kaczor, Kacper Fiedurek, Krzysztof Bajer, Aneta Raszkowska-Kaczor, Grzegorz Domek, Marek Macko, Piotr Madajski and Pawel Szroeder
Materials 2021, 14(18), 5346; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14185346 - 16 Sep 2021
Cited by 7 | Viewed by 1752
Abstract
To assess the impact of graphite fillers on the thermal processing of graphite/poly(lactic acid) (PLA) composites, a series of the composite samples with different graphite of industrial grade as fillers was prepared by melt mixing. The average size of the graphite grains ranged [...] Read more.
To assess the impact of graphite fillers on the thermal processing of graphite/poly(lactic acid) (PLA) composites, a series of the composite samples with different graphite of industrial grade as fillers was prepared by melt mixing. The average size of the graphite grains ranged between 100 µm and 6 µm. For comparative purposes, one of the carbon fillers was expandable graphite. Composites were examined by SEM, FTIR, and Raman spectroscopy. As revealed by thermogravimetric (TG) analyses, graphite filler slightly lowered the temperature of thermal decomposition of the PLA matrix. Differential scanning calorimetry (DSC) tests showed that the room temperature crystallinity of the polymer matrix is strongly affected by the graphite filler. The crystallinity of the composites determined from the second heating cycle reached values close to 50%, while these values are close to zero for the neat polymer. The addition of graphite to PLA caused a slight reduction in the oxidation induction time (OIT). The melt flow rate (MFR) of the graphite/PLA composites was lower than the original PLA due to an increase in flow resistance associated with the high crystallinity of the polymer matrix. Expandable graphite did not cause changes in the structure of the polymer matrix during thermal treatment. The crystallinity of the composite with this filler did not increase after first heating and was close to the neat PLA MFR value, which was extremely high due to the low crystallinity of the PLA matrix and delamination of the filler at elevated temperature. Full article
(This article belongs to the Special Issue Feature Paper in Section Materials Chemistry)
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22 pages, 6007 KiB  
Article
Acenaphthoquinoxaline Derivatives as Dental Photoinitiators of Acrylates Polymerization
by Ilona Pyszka and Beata Jędrzejewska
Materials 2021, 14(17), 4881; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14174881 - 27 Aug 2021
Cited by 2 | Viewed by 1639
Abstract
A series of dyes based on the acenaphthoquinoxaline skeleton was synthesized. Their structure was modified by introducing electron-withdrawing and electron-donating groups, increasing the number of conjugated double bonds and the number and position of nitrogen atoms, as well as the arrangement of aromatic [...] Read more.
A series of dyes based on the acenaphthoquinoxaline skeleton was synthesized. Their structure was modified by introducing electron-withdrawing and electron-donating groups, increasing the number of conjugated double bonds and the number and position of nitrogen atoms, as well as the arrangement of aromatic rings (linear or angular). The dyes were investigated as a component in the photoinitiating systems of radical polymerization for a potential application in dentistry. They acted as the primary absorber of visible light and the acceptor of an electron, which was generated from a second component being an electron donor. Thus, the radicals were generated by the photoinduced intermolecular electron transfer (PET) process. Electron donors used differed in the type of heteroatom, i.e., O, S and N and the number and position of methoxy substituents. To test the ability to initiate the polymerization reaction by photoinduced hydrogen atom transfer, we used 2-mercaptobenzoxazole as a co-initiator. The effectiveness of the photoinitiating systems clearly depends on both the modified acenaphthoquinocaline structure and the type of co-initiator. The lower amount of heat released during the chain reaction and the polymerization rate comparable to this achieved for the photoinitiator traditionally used in dentistry (camphorquinone) indicates that the studied dyes may be valuable in this field. Full article
(This article belongs to the Special Issue Feature Paper in Section Materials Chemistry)
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14 pages, 1249 KiB  
Article
M(II)Al4 Type Layered Double Hydroxides—Preparation Using Mechanochemical Route, Structural Characterization and Catalytic Application
by Márton Szabados, Adél Anna Ádám, Zsolt Kása, Kornélia Baán, Róbert Mucsi, András Sápi, Zoltán Kónya, Ákos Kukovecz and Pál Sipos
Materials 2021, 14(17), 4880; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14174880 - 27 Aug 2021
Cited by 6 | Viewed by 1781
Abstract
The synthesis of the copper-poor and aluminum-rich layered double hydroxides (LDHs) of the CuAl4 type was optimized in detail in this work, by applying an intense mechanochemical treatment to activate the gibbsite starting reagent. The phase-pure forms of these LDHs were prepared [...] Read more.
The synthesis of the copper-poor and aluminum-rich layered double hydroxides (LDHs) of the CuAl4 type was optimized in detail in this work, by applying an intense mechanochemical treatment to activate the gibbsite starting reagent. The phase-pure forms of these LDHs were prepared for the first time; using copper nitrate and perchlorate salts during the syntheses turned out to be the key to avoiding the formation of copper hydroxide sideproducts. Based on the use of the optimized syntheses parameters, the preparation of layered triple and multiple hydroxides was also attempted using Ni(II), Co(II), Zn(II) and even Mg(II) ions. These studies let us identify the relative positions of the incorporating cations in the well-known selectivity series as Ni2+ >> Cu2+ >> Zn2+ > Co2+ >> Mg2+. The solids formed were characterized by using powder X-ray diffractometry, UV–Vis diffuse reflectance spectroscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. The catalytic potential of the samples was investigated in carbon monoxide oxidation reactions at atmospheric pressure, supported by an in situ diffuse reflectance infrared spectroscopy probe. All solids proved to be active and the combination of the nickel and cobalt incorporation (which resulted in a NiCoAl8 layered triple hydroxide) brought outstanding benefits regarding low-temperature oxidation and increased carbon monoxide conversion values. Full article
(This article belongs to the Special Issue Feature Paper in Section Materials Chemistry)
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13 pages, 1950 KiB  
Article
Indentation Response of Calcium Aluminoborosilicate Glasses Subjected to Humid Aging and Hot Compression
by Xiangting Ren, Pengfei Liu, Sylwester J. Rzoska, Boleslaw Lucznik, Michal Bockowski and Morten M. Smedskjaer
Materials 2021, 14(13), 3450; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14133450 - 22 Jun 2021
Cited by 1 | Viewed by 1459
Abstract
Aluminoborosilicate glasses find a wide range of applications, which require good mechanical reliability such as surface damage resistance. Calcium aluminoborosilicate (CABS) glasses have recently been found to exhibit so-called intermediate behavior in terms of their response to sharp contact loading. That is, these [...] Read more.
Aluminoborosilicate glasses find a wide range of applications, which require good mechanical reliability such as surface damage resistance. Calcium aluminoborosilicate (CABS) glasses have recently been found to exhibit so-called intermediate behavior in terms of their response to sharp contact loading. That is, these glasses deform with less shear than normal glass and less densification than anomalous glasses. This deformation mechanism is believed to give rise to high crack initiation resistance of certain CABS glasses. In order to further improve and understand the micromechanical properties of this glass family, we studied the indentation response of different CABS glasses subjected to two types of post-treatment, namely hot compression and humid aging. Upon hot compression, density, elastic moduli, and hardness increased. Specifically, elastic modulus increased by as much as 20% relative to the as-made sample, while the largest change in hardness was 1.8 GPa compared to the as-made sample after hot compression. The pressure-induced increase in these properties can be ascribed to the increase in network connectivity and bond density. On the other hand, the crack initiation resistance decreased, as the hot compression increased the residual stress driving the indentation cracking. Humid aging had only a minor impact on density, modulus, and hardness, but an observed decrease in crack initiation resistance. We discuss the correlations between hardness, density, crack resistance, and deformation mechanism and our study thus provides guidelines for tailoring the mechanical properties of oxide glasses. Full article
(This article belongs to the Special Issue Feature Paper in Section Materials Chemistry)
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19 pages, 9059 KiB  
Article
A Cellulose-Derived Nanofibrous MnO2-TiO2-Carbon Composite as Anodic Material for Lithium-Ion Batteries
by Shun Li, Ming Yang, Guijin He, Dongmei Qi and Jianguo Huang
Materials 2021, 14(12), 3411; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14123411 - 20 Jun 2021
Cited by 2 | Viewed by 1956
Abstract
A bio-inspired nanofibrous MnO2-TiO2-carbon composite was prepared by utilizing natural cellulosic substances (e.g., ordinary quantitative ashless filter paper) as both the carbon source and structural matrix. Mesoporous MnO2 nanosheets were densely immobilized on an ultrathin titania film precoated [...] Read more.
A bio-inspired nanofibrous MnO2-TiO2-carbon composite was prepared by utilizing natural cellulosic substances (e.g., ordinary quantitative ashless filter paper) as both the carbon source and structural matrix. Mesoporous MnO2 nanosheets were densely immobilized on an ultrathin titania film precoated with cellulose-derived carbon nanofibers, which gave a hierarchical MnO2-TiO2-carbon nanoarchitecture and exhibited excellent electrochemical performances when used as an anodic material for lithium-ion batteries. The MnO2-TiO2-carbon composite with a MnO2 content of 47.28 wt % exhibited a specific discharge capacity of 677 mAh g−1 after 130 repeated charge/discharge cycles at a current rate of 100 mA g−1. The contribution percentage of MnO2 in the composite material is equivalent to 95.1% of the theoretical capacity of MnO2 (1230 mAh g−1). The ultrathin TiO2 precoating layer with a thickness ca. 2 nm acts as a crucial interlayer that facilitates the growth of well-organized MnO2 nanosheets onto the surface of the titania-carbon nanofibers. Due to the interweaved network structures of the carbon nanofibers and the increased content of the immobilized MnO2, the exfoliation and aggregation, as well as the large volume change of the MnO2 nanosheets, are significantly inhibited; thus, the MnO2-TiO2-carbon electrodes displayed outstanding cycling performance and a reversible rate capability during the Li+ insertion/extraction processes. Full article
(This article belongs to the Special Issue Feature Paper in Section Materials Chemistry)
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19 pages, 5417 KiB  
Article
Effective Singlet Oxygen Sensitizers Based on the Phenazine Skeleton as Efficient Light Absorbers in Dye Photoinitiating Systems for Radical Polymerization of Acrylates
by Ilona Pyszka, Zdzisław Kucybała and Beata Jędrzejewska
Materials 2021, 14(11), 3085; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14113085 - 04 Jun 2021
Cited by 5 | Viewed by 1943
Abstract
A series of dyes based on the phenazine skeleton were synthesized. They differed in the number of conjugated double bonds, the arrangement of aromatic rings (linear and/or angular system), as well as the number and position of nitrogen atoms in the molecule. These [...] Read more.
A series of dyes based on the phenazine skeleton were synthesized. They differed in the number of conjugated double bonds, the arrangement of aromatic rings (linear and/or angular system), as well as the number and position of nitrogen atoms in the molecule. These compounds were investigated as potential singlet oxygen sensitizers and visible light absorbers in dye photoinitiating systems for radical polymerization. The quantum yield of the singlet oxygen formation was determined by the comparative method based on the 1H NMR spectra recorded for the tested dyes in the presence of 2,3-diphenyl-p-dioxene before and after irradiation. The quantum yield of the triplet state formation was estimated based on the transient absorption spectra recorded using the nanosecond flash photolysis technique. The effectiveness of the dye photoinitiating system was characterized by the initial rate of trimethylolpropane triacrylate (TMPTA) polymerization. In the investigated photoinitiating systems, the sensitizer was an electron acceptor, whereas the co-initiator was an electron donor. The effectiveness of TMPTA photoinitiated polymerization clearly depended on the arrangement of aromatic rings and the number of nitrogen atoms in the modified phenazine structure as well as the quantum yield of the triplet state formation of the photosensitizer in the visible light region. Full article
(This article belongs to the Special Issue Feature Paper in Section Materials Chemistry)
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11 pages, 2285 KiB  
Article
Preparation and Characterization of a Novel Vinyl Polysiloxane Getter for Hydrogen Elimination
by Tao Xing, Yong Xu, Juying Wu, Yu Wang and Lifeng Yan
Materials 2021, 14(8), 1853; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14081853 - 08 Apr 2021
Cited by 3 | Viewed by 1671
Abstract
Hydrogen generation and accumulation in confined spaces poses safety concerns due to its reactivity with oxygen to form explosions and the ability to embrittle metals. Various organic getters have been developed to eliminate hydrogen and minimize these undesired effects; however, these getters are [...] Read more.
Hydrogen generation and accumulation in confined spaces poses safety concerns due to its reactivity with oxygen to form explosions and the ability to embrittle metals. Various organic getters have been developed to eliminate hydrogen and minimize these undesired effects; however, these getters are usually powders with low molecular weights and are difficult to apply in complex structures. Polymer getters exhibit the promising features required for confined space applications, where could be readily processed into various shapes and forms. Unfortunately, polymer getters are relatively unexplored and their recorded performances are far from satisfactory. In this work, we report the preparation and characterization of novel vinyl polysiloxane getters. Starting from a methyl vinyl silicone oil prepared by ring-opening polymerization, polysiloxane getters in versatile forms that are adaptable to various environments are prepared by adding Pd/C and then curing. Combined with the thermal and radiation stability of polysiloxane, not only will these new getters be applicable in future applications in the electronic and nuclear industries as hydrogen scavengers, they also serve as platform for further development of polymer getters with superior properties. Full article
(This article belongs to the Special Issue Feature Paper in Section Materials Chemistry)
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