Search

The intensive use of fossil fuels has profound impacts on all ecosystems, primarily contributing to global warming through greenhouse gas emissions. To mitigate these impacts, alternative energy sources like hydrogen are crucial. In this study, azo cross‐linked polymer with 4‐aminophenyl sulfone and resorcinol were synthesized by a green synthesis method. The polymer was extensively characterized by Fourier‐transform infrared spectroscopy, Brunner‐Emmett‐Teller analysis, thermogravimetric analysis, and scanning electron microscopy‐energy dispersive x‐ray spectroscopy analyses. Subsequently, the catalytic performance of the polymer in hydrogen production from NaBH4 via methanolysis was investigated. At this stage, the parameters affecting hydrogen production (catalyst and NaBH4 amounts, MeOH volume and temperature) were systematically studied to determine optimum conditions. The maximum HGR values of the polymer was 13,100 and 27,000 mL min−1 gcat−1 at 30 and 60°C, respectively and its activation energy was 10.45 kJ mol−1. After optimization, the reusability of azo polymer was tested with 5 cycles. The theoretical volume of hydrogen was produced in all 5 cycles. But with each cycle, the hydrogen production time increased. The main purpose of this study was to demonstrate novel azo‐linked polymers with high catalytic activity in hydrogen production. The results revealed significant potential of the polymer for hydrogen generation. Overall, this research highlights the promising role of azo cross‐linked polymers as effective catalysts for hydrogen production, offering new perspectives and pathways towards sustainable energy solutions. [ABSTRACT FROM AUTHOR]

In this study, trimethylolpropane triglycidyl ether/diethylenetriamine (TD) and glutaraldehyde/diethylenetriamine (GD) polymer particles are synthesized as catalysts for hydrogen production from NaBH4 methanolysis and NaBH4 electrooxidation. SEM, FT‐IR and TGA characterization methods are applied to determine the surface morphologies, chemical structures, thermal stability and decomposition of the synthesized polymer particles. The parameters affecting the hydrogen generation rate on NaBH4 methanolysis are investigated and optimum conditions are determined. Under optimum conditions, the hydrogen generation rates of TD and GD polymer particles are obtained as 34903.2 and 97998 mL/min.gcat, respectively. The activation energies of TD and GD polymer particles are also calculated as 16.86 and 18.14 kJ/mol, respectively. The catalytic activities of polymer particles as anode catalysts in NaBH4 electrooxidation are determined by CV, CA, EIS analyses. The specific activities of TD and GD polymer particles are acquired as 0.54 and 0.64 mA/cm2, respectively. These results indicate that the synthesized polymer particles are promising catalysts for electrooxidation and methanolysis of sodium borohydride. [ABSTRACT FROM AUTHOR]

Cross-linked and flexible poly(vinyl acetone ketal) (PV-A-K) films have been prepared as a result of ketalization reaction and monolith formation of poly(vinyl alcohol) (PVA), which has the feature of forming films quickly and is frequently used in biological fields. In this novel method, flexible PVA-K films have been produced simply and in a short time accompanied by monolith formation without any catalyst in acetone. The effect of acetone ratio on the physical properties (i.e., swelling and mechanical properties) of such formations has been investigated to reveal significant influences of it. In addition, zinc oxide (ZnO) nanoparticles synthesized via the solvothermal method have been doped into PV-A-K films during film preparation. The prepared PV-A-K and ZnO doped PV-A-K films have been characterized with SEM, XRD, and FT-IR. Their mechanical properties have been investigated with a universal mechanical test machine. The acetone ratio is quite effective both on the porosity and stress/strain properties of the films. Antibacterial activities of the films are evaluated against four different strains (E. coli, S. aureus, P. aeruginosa, and E. faecalis) via the disk diffusion method. The films are selectively effective against S. aureus. These highly flexible and elastic films have great potential for biomedical applications, wound dressing, and antibacterial surface preparation. [ABSTRACT FROM AUTHOR]

In situ preparation of bifunctional thiazolo[5,4‐d]thiazole (TTz)‐based fluorophore cross‐linked nanofibers is successfully performed. These multifunctional nanofibers are used as both crystal growth template and antibacterial substrate that makes bacterial detection possible simultaneously. These highly fluorescent nanofibers act as optical sensors toward many analytes. The acid, base, and metal cation‐sensitive nature of the 2,5‐bis(4‐hydroxyphenyl)thiazolo[5,4‐d]thiazole (HPhTT) dye makes the prepared PVA nanofibers sensitive against these chemicals. Metal nanoparticles (MNPs) or metal oxide crystal formation occurs on the surface of nanofibers without any reducing agent. The strong interaction between metal cations and fluorophores results in crystal formation on the surface, which is named for the first time as "complexation‐triggered crystalization." These dye cross‐linked and metal‐interacted nanofibers exhibit antibacterial effect against E. coli (ATCC 25922), S. aureus (ATCC 25923), P. aeruginosa (ATCC 27853), and E. faecalis (ATCC 25922) strains. Also, the emission wavelength change of nanofibers in bacterial contamination makes it possible to use smart nanofiber films for optical bacteria detection. These novel materials pave the way for new applications such as smart wound bands, optical sensors, and one‐step preparation of surface‐enhanced Raman spectroscopy substrate. [ABSTRACT FROM AUTHOR]

ABC-type triblock copolymers, namely poly[(ethylene glycol)methyl ether]-block-poly(tert-butyl methacrylate)-blockpoly[ 2-N-(diisopropylamino)ethyl methacrylate] (MPEG-b-PBuMA-b-PDPA), were first synthesized and then the middle blocks were successfully converted into poly(methacrylic acid) to obtain MPEG-b-PMAA-b-PDPA zwitterionic triblock copolymers. These block copolymers were soluble in water and formed micellar aggregates with complex cores via hydrogen bonding interactions between MPEG and PMAA blocks below pH 4.0. When the pH was between 5.0 and 7.0, due to charge compensation between partially protonated PDPA and partially ionized PMAA blocks, micelles with polyion complex cores were observed. If the solution pH was above 8.0, deprotonation of tertiary amine groups provided a hydrophobic character to the PDPA block, which resulted in the formation of PDPAcore micelles while MPEG/anionic PMAA hybrid blocks formed hydrated coronas. Intermediary layer cross-linked (ILCL) micelles from PDPA-core micelles were also prepared by cross-linking the inner PMAA shell. The hydrophobic drug dipyridamole (DIP) was used to investigate the release profile of ILCL micelles. DIP can be loaded to the PDPA cores of the micelles in basic aqueous media. An increase in the degree of cross-linking causes slower release for the model drug. It was concluded that the more complex matrix formation in the intermediary layer of the micelles via cross-linking retards the drug release from the core. [ABSTRACT FROM AUTHOR]

The aim of this study is to highlight the use of polystyrene (PS) latexes stabilized with block copolymers as a hard template in the production of metal oxide hollow spheres. PS latexes produced by dispersion polymerization by stabilizing with tertiary amine methacrylate-based diblock copolymer were used as a hard template in the preparation of nickel manganese oxide (NiMn2O4) hollow spheres and cobalt iron oxide (CoFe2O4) bowl-like structures. Thanks to the diblock copolymer stabilizer with tertiary amine functional groups on the PS surface, precursor salts of CoFe2O4 and NiMn2O4 were first homogeneously deposited on the surface of PS latexes with a controlled precipitation technique. Then, metal oxide hollow spheres and bowl-like structures were produced by calcination. XRD results showed that CoFe2O4 and NiMn2O4 structures were successfully obtained after calcination. The thermogravimetric analysis results showed that the CoFe2O4 and NiMn2O4 contents of the hybrid PS spheres were in the range of 26.0-28.6 wt%. SEM images showed that the inorganic-polymer spheres fused with each other after calcination to form larger magnetic CoFe2O4 bowl-like structures. SEM images also indicated successful production of highly rough NiMn2O4 hollow spheres with nanosheets on the surface. [ABSTRACT FROM AUTHOR]

Hollow spheres of nickel oxide (NiO) and silver, gold, and platinum nanoparticle loaded NiO composites were successfully produced by using polystyrene (PS) latexes as hard template. Due to the presence of tertiary amine based diblock copolymer stabilizer on the surface of PS, the tertiary amine functional groups provided homogene deposition of nickel hydroxide, and then the precursor NiO salt production on the surface of PS latexes with a controlled precipitation technique. Then, NiO and NiO/metal NP hollow spheres were produced by calcination at 600 °C. Thermogravimetric analysis indicated that the amounts of NiO and NiO‐composite after calcination were in the range of 21.1–29.7 wt%. The diameters of metal oxide spheres were in the range of 2.0–2.7 μm and the shell thickness were in the range of 250–350 nm. These structures had very low densities due to their porous and hollow structures and had outer layers with highly rough surfaces due to formation of nanosheets, which may offer important advantages for catalysis studies. [ABSTRACT FROM AUTHOR]