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91.
92.
Marine Harguindeguy Claire Antonelli Marie-Pierre Belleville José Sanchez-Marcano Céline Pochat-Bohatier 《应用聚合物科学杂志》2021,138(2):49669
Millimeter-size beads of gelatin are manufactured by dripping process to give enzyme supports qualified for micropollutants biodegradation in alternative wastewater treatment. The bead diameter is dependent on the tip diameter, the gelatin solution viscosity and the swelling of polymer chains in the collecting bath. Chemical crosslinking was performed with glutaraldehyde using optimal concentration to give mechanical and thermal properties suitable for application in stirred reactor in aqueous medium. Laccases from Trametes versicolor are grafted on the gelatin beads with glutaraldehyde. Sixty percentage of the initial enzymatic activity, evaluated by the oxidation of 2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) is maintained after 10 successive cycles of reaction. Thermal stability at 60°C of immobilized biocatalysts is improved when compared to free enzymes (45% vs 10% of relative activity after 6 h of incubation). The simplicity of the procedure to form gelatin beads and their properties make them promising bio-based and biodegradable support for enzyme immobilization. 相似文献
93.
Seong-Joong Kim Yeojin Ahn Jeong F. Kim Seung-Eun Nam Hosik Park Young Hoon Cho Kyung-youl Baek You-In Park 《应用聚合物科学杂志》2021,138(7):49860
To overcome the plasticization effect in polyimide membranes, many researchers have proposed crosslinking method. This can reduce an inter-segmental mobility by tightening and rigidifying the polymer chains. However, it is difficult to modify the whole polymer chains throughout the membrane because the reaction can be hindered by the diffusion rate of the crosslinker. In particular, it is hard for bulky crosslinker to penetrate a dense membrane with a small d-spacing. This study investigated the effect of crosslinking a dense Matrimid membrane with p-phenylenediamine (p-PDA) via two different crosslinking methods (i.e., methanol-swelling crosslinking process [M-SCP] and liquid-phase crosslinking process [L-PCP]). Most of the crosslinking reaction in M-SCP occurs on the membrane surface due to difficulty in penetration of the bulky p-PDA into the Matrimid dense membrane. In contrast, the L-PCP allows uniform crosslinking across the membrane. The membranes crosslinked using L-PCP showed excellent chemical resistance. Furthermore, the plasticization phenomenon was not observed in the membranes crosslinked using L-PCP with p-PDA more than 15%. Meanwhile, the membrane crosslinked using M-SCP exhibited poor plasticization and chemical resistance properties. These results showed that the L-PCP method can be more effective for the crosslinking of dense membrane to deliver both high plasticization and chemical resistance. 相似文献
94.
The preparation and application of hydrogel has been a hot research field in recent years. Here in, a composite hydrogel based on poly(vinyl alcohol) (PVA), carboxymethyl chitosan (CMCS), oxidized sodium alginate (OSA), and oxidized multiwall carbon nanotubes (OMWCNTs) was successfully prepared. Hydrogen and imine bonds of the hydrogel endowed the composite hydrogel with self-healing property and pH sensitivity. The fracture strength of the hydrogel was enhanced to about 0.8 MPa with the help of OMWCNTs, which was about 2.5 times compared with the one without OMWCNTs. Meanwhile, a new conductive network inside the hydrogel was constructed by OMWCNTs, which improved the conductivity of the hydrogel from 1.75 × 10−4 to 7.02 × 10−4 S/cm. The sensing test of the hydrogel showed that it could produce profound feedback signals for the deformation caused by external force and response to human body movements, such as finger bending, swallowing, and speaking. 相似文献
95.
Hailin Yu Yifan Xia Hanwen Zhang Xinjian Gong Pengfei Geng Zhenwei Gao Yinghan Wang 《应用聚合物科学杂志》2021,138(6):49803
In this work, semiinterpenetrating polymer network (semi-IPN), consisting of sulfonated poly (arylene ether sulfone) (SPAES) and crosslinked vinyl imidazole grafted polysulfone (VMPSU), is prepared and characterized. FTIR, EDS, and solubility test indicate the successful preparation of amphoteric membranes. The semi-IPN amphoteric membranes exhibit better stability than pure SPAES membrane, as demonstrated by thermogravimetric analysis and ex situ immersion testing results. More importantly, it is shown that the amphoteric membrane can effectively hinder vanadium ion crossover through the membrane, which is attributed to the semi-IPN structure and Donnan exclusion. As expected, the amphoteric membrane containing 20% VMPSU exhibits the highest proton selectivity (6.86 × 104 S min cm−3), comparing to pristine SPAES (1.90 × 104 S min cm−3) as well as Nafion117 (1.31 × 104 S min cm−3). 相似文献
96.
Mollie B. Schear Arianna Neal Jadah S. Clarke Andrew P. Saab Carl B. Giller Riccardo Casalini Matthew Laskoski 《应用聚合物科学杂志》2021,138(12):50053
The preparation of highly aromatic elastomers from a bisphenol A-based divinyl-terminated resin and polymerization with various aromatic silane containing compounds utilizing a room temperature hydrosilylation reaction is demonstrated. The polymers exhibit high thermal and oxidative stability with 5% weight losses around 430 and 350°C and char yields ranging from 35% to 40%. The thermosets maintained their elastomeric properties with good hardness and mechanical properties as measured by elongation measurements. The toughness of the thermosets was not improved with the inclusion of aromatic moieties but the hardness did appear to increase with the addition of more aromatic groups. 相似文献
97.
Hybrid anion exchange membranes (AEMs) were prepared via chemically functionalizing and crosslinking poly(styrene-b-[ethylene-co-butylene]-b-styrene) (SEBS) copolymers and low molecular weight homo-polystyrene (hPS). Via sequential chloromethylation, crosslinking, quaternization, and alkalization, a series of hPS/SEBS AEMs were obtained with varying content of hPS. Systematic structural, morphological, mechanical, absorption, and transport measurements reveal that these properties depend on the total PS content in the membranes. Particularly, increasing total PS content causes (a) PS domains in the AEMs transition the cylindrical morphology to lamella-like morphology with comparable correlation length; (b) Young's modulus, water uptake, swelling ratio, ionic exchange capacity and ionic conductivity of the AEMs, and Tg of PS phase increase. In addition, the alkaline stability of the hPS/SEBS AEMs is also improved by addition of hPS. These findings suggest that the proposed method can develop high performance SEBS AEMs that are suitable for fuel cell applications. 相似文献
98.
Linear polyethyleneimine (L-PEI)-based nanoparticles were synthesized via hydrolysis of poly-2-methyl-2-oxazoline (PMeOx), which was prepared by cationic ring-opening polymerization of the oxazoline five-membered ring. Herein, a kinetic study of the ring-opening polymerization reaction is discussed. The nuclear magnetic resonance spectrum of PMeOx verified the presence of repeating units and terminal groups in the polymer's structure. Molar ratios of PEI and PMeOx were characterized using size exclusion chromatography with low-polydispersity polymer chains as the controlled polymerization reaction. PEI and PMeOx exhibited narrow particle size distribution with hydrodynamic radii of 89 and 67 nm, respectively, as determined via dynamic light scattering analysis. In addition, atomic forces and scanning electron microscopy were used to investigate the topography of the PEI thin films. Poly(glycidyl methacrylate) P(GMA) was grafted onto a PEI chain in the presence of trimethylolpropane triacrylate (TMPTA) as the crosslinking agent to synthesize the P(GMA–PEI–TMPTA) tripolymer via free radical polymerization using gamma irradiation. The thermal characterization of the P(GMA–PEI–TMPTA) tripolymer was conducted using thermogravimetric analysis and differential scanning calorimeter. Generally, the thermal stability of the P(GMA–PEI–TMPTA) tripolymer was improved at low-glycidyl methacrylate concentrations. The prepared tripolymer could be used as effective packaging materials for electronics industries. 相似文献
99.
Rajabali Ebrahimi 《应用聚合物科学杂志》2021,138(37):50931
The powerful waves of ultrasound are used in polymerization reactions in the absence of initiator. In the present research, the hydrogel was obtained by water-soluble acrylic monomers, starch, and the crosslinking agent of methylene bis acrylamide dissolved in water/glycerol dual. The hydrogel is formed by these waves only in viscous environments such as glycerol, heat, or initiator is not required. In the presence of ultrasound, the time of product formation is reduced to a few minutes. Moreover, the resulting hydrogels have more uniform microscopic structure and are more swollen. The structure of the grafted hydrogel was examined meanwhile the hydrogel swelling in three environments of pure water, saltwater, and under pressure was measured. It was found that the grafted hydrogel has double swelling rate in the pure. Also, after loading the ciprofloxacin into the synthesized hydrogel, this drug is released 99% in initial 20 min. 0.1 g starch in 1.5 g acrylic hydrogel has the most drug release. The high swelling capacity in the pH ranges of 5–9 shows the extension of drug application in acidic or alkaline environments, and also after several using the gel and the capacity of water absorbency, which was about 70% of its initial water, indicates the perfect reusability capacity of the gel. 相似文献
100.
A semi-interpenetrating polymer network superabsorbent polymer based on sodium lignosulfonate-graft-poly(acrylic acid-acrylamide)/potassium dihydrogen phosphate and polyvinyl alcohol (PVA/SL-g-P[AA-AM]/KDP) was synthesized by using solution polymerization. The PVA/SL-g-P(AA-AM)/KDP was further hydrolyzed in NaOH solution. The structure, thermal stability, and morphologies of samples were examined by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results of FTIR, TGA, and DSC showed that PVA interpenetration through SL-g-P(AA-AM)/KDP network has occurred, and PVA/SL-g-P(AA-AM)/KDP was successfully alkaline hydrolyzed. From the SEM images, the high porous and loose surface structure of polymers was formed after hydrolysis, which greatly increased the specific surface area. Samples after hydrolysis exhibited higher equilibrium swelling capacity (1963 g/g) compared to the nonhydrolyzed samples (866 g/g). The swelling kinetics of all samples well complied with the pseudo-second order swelling kinetics model. Simple hydrolysis treatment not only improved the swelling capacity of PVA/SL-g-P(AA-AM)/KDP but also induced an enhancement on its water retention performance, which made it potentially useful as a water retention agent in the revegetation of abandoned mines or slope wasteland. 相似文献