Novel hydrophilic N-halamine polymer with enhanced antibacterial activity synthesized by inverse emulsion polymerization

N-halamine-based antibacterial agents have high efficiency and rechargeable antibacterial properties. However, their applications are limited due to their complex synthetic process and fuzzy antibacterial mechanism. In this study, a novel N-halamine antibacterial polymer was synthesized by inverse emulsion polymerization and characterized by Fourier transform infrared, nuclear magnetic resonance, scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. Due to the difficulty of purification, most of the subjects studied previously were hydrophobic polymers, while little research on hydrophilic polymers. In this experiment, this difficulty was overcome by controlling the dosage of sodium hypochlorite and methods of dialysis. Because of the complex cell structure of Gram-negative bacteria, it is difficult for N-halamines to release the oxidizing chlorine into the cell. However, the hydrophilic N-halamines can solve this problem, which showed a stronger antibacterial effect on Gram-negative Escherichia coli synthesized in this study. In addition, the particle size and hydrophilic property of the polymer were changed by changing the amount of initiator, and the differences in their antibacterial properties were studied. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47419.     

New water-soluble copolymers of 2-methacryloyloxyethyl phosphorylcholine for surface modification

New copolymers of 2-methacryloyloxyethyl phosphorylcholine with 2-Deoxy-2-methacrylamido-D-glucose, N-vinylpyrrolidone, and N-vinyl-N-methylacetamide were synthesized and characterized; the obtained copolymers contained 10–50 mol% of phosphorylcholine moieties, and their molecular masses ranged from 1.05 × 10⁵ to 4.40 × 10⁵. Reactivity ratios of the monomers were estimated. Conformational states of the copolymers in aqueous solutions were studied. The synthesized copolymer was grafted onto the surface of carbon fiber biosorbent using γ-radiation.     

Poly(ether-block-amide) membrane with deformability and adjustable surface hydrophilicity for water purification

Freshwater resources are currently insufficient, and another form of freshwater resources, namely, ice, is very interesting except for the issue of how to use new materials for effective purification during the processing procedure. In this article, a new membrane material with multisize pore structure in the cross-section and intact thin skin layer on the upper and lower surfaces was successfully prepared by adding porogen, filler and setting heating environment during the phase separation process. The membrane exhibits excellent axial deformability, and its elongation at break can reach to 160% strain. Meanwhile, they all show elastic deformation behavior in the range from −60 to 100°C. Even if high content of hydrophobic filler is compounded into these membranes, that is, 5.7 wt% carbon tube content, water contact angle of membrane's surface is only 72.5°, demonstrating obvious hydrophilicity. In addition, in the water purification process, the adsorption rate constant reached ideal value of 0.26 s⁻¹, and the equilibrium adsorption capacity was about 2.8 g/g, showing fast and efficient water purification ability. In the mode of external heating source or the membrane's heat dissipation, these prepared membranes can melt the ice to obtain purified water and exhibit a controllable purification ability in this process.     

亲水性PET共混材料的制备及性能研究

以机械共混法制备亲水性聚对苯二甲酸乙二醇酯（PET）共混材料，并通过接触角测定仪、差示扫描量热仪(DSC)和电子万能材料试验机等对共混材料的亲水性能、热性能和力学性能等进行研究与分析。结果表明，亲水处理剂聚乙二醇（PEG）、聚丙烯酸钠（PAAS）、聚乙烯吡咯烷酮（PVP）均能改善PET的亲水性能，影响PET的结晶性能，但亲水处理剂对PET的力学性能影响较小，其中PET/PEG共混材料的亲水性最优；随着PEG含量的增加，PET/PEG共混材料的亲水性先逐渐增强，当PEG含量高于5 %后，共混材料的亲水性变化很小；且PET的结晶度随着PEG的加入呈现先增大后减小的趋势。     

Fabrication of antifouling membranes by blending poly(vinylidene fluoride) with cationic polyionic liquid

Membrane fouling problem is now limiting the rapid development of membrane technology. A newly synthesized cationic polyionic liquid (PIL) [P(PEGMA-co-BVIm-Br)] was blended with poly(vinylidene fluoride) (PVDF) to prepare antifouling PVDF membranes. The PVDF/P(PEGMA-co-BVIm-Br) exhibited an increased surface hydrophilicity, the water contact angle was reduced from 77.8° (pristine PVDF) to 57.9°. More porous membrane structure was obtained by adding PIL into the blending polymers, as high as 478.0 L/m²·h of pure water flux was detected for the blend PVDF membrane in comparison with pristine PVDF (17.2 L/m²·h). Blending of the cationic PIL with PVDF gave a more positive surface charge than pristine PVDF membrane. Blend membranes showed very high rejection rate (99.1%) and flux recovery rate (FRR, 83.0%) to the positive bovine serum albumin (BSA), due to the electrostatic repulsion between the membrane surface and proteins. After three repeated filtration cycles of positive BSA, the blend PVDF membranes demonstrated excellent antifouling performance, the permeation flux of the membranes was recovered very well after a simple deionized water washing, and as high as 70% of FRR was obtained, the water flux was maintained at above 350 L/m²·h. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48878.     

Bactericidal effect of cationic hydrogels prepared from hydrophilic polymers

This study investigated whether hydrogels comprising hydrophilic cationic polymers have similar bactericidal effects. Bacteria were seeded on hydrogels and agar and their viability was assessed with time. Cationic hydrogels displayed bactericidal effects upon long-term bacterial contact. Furthermore, we assessed the areal density of cationic monomer unit of the cationic hydrogels, water content, and the initial elastic modulus. We examined correlations between each factor and bacterial death ratios; consequently, the bacterial death ratios were strongly correlated with the areal density of cationic hydrogel monomers. Elastic energy (W_el) generated at the cytomembrane ion-binding region and the cationic hydrogel and the cytomembrane interfacial energy (W_f) were estimated; consequently, W_el exceeded W_f at higher contact areas. The cationic hydrogel may extract cytomembranes with a reasonable adsorption area. Therefore, cationic hydrogels may be used as probes for ultrasonic echo to sterilize medical equipment.     

Swelling behavior of expandable poly(methyl methacrylate-acrylic acid)/polymethyl methacrylate bio-composites with different crosslinking densities

The volume shrinkage of poly(methyl methacrylate-acrylic acid) (PMMA) bone cement was mainly tackled by the different types and contents of the hydrophilic additives. While the crosslinking density was assumed to regulate the hydrophilic group amounts and 3D network structures in the additives, which influenced the absorption and swelling capacity of the PMMA-based bone cement. In this study, the expandable PMMA/polymethyl methacrylate bio-composites (EBC) with different N, N-methylenebisacrylamide (MBA) contents were synthesized to investigate the relationship between the crosslinking density and swelling performance, and also promoted the absorption and swelling properties before the solidification of EBC. The results demonstrated that the equilibrium absorption ratio and the equilibrium swelling ratio both exhibited a normal distribution with the various MBA content. In addition, the controlled absorption ratio (7.3–60.2%) and swelling ratio (8.5–61.8%) of EBC could be obtained by altering crosslinking density in the system. Furthermore, EBC could obtain a similar equilibrium absorption ratio and equilibrium swelling ratio with different mechanical properties, which provided more options for meeting the requirements of EBC in different clinical settings.     

Preparation of organic–inorganic hybridized dual-functional antifog/antireflection coatings on plastic substrates

Dual-functional antifog/antireflection coatings with a special bi-layer structure for plastic substrates were prepared. The superhydrophilic top layer was a crosslinked network of dipentaerythritol hexaacrylate (DPHA), hydrophilic agent (synthesized from Tween 20, isophorone diisocyanate, 2-hydroxyethyl methacrylate), and organically modified silica. The high-refractive-index bottom layer was composed of TiO₂ nanoparticles and DPHA. The two layers were chemically bonded through a UV-curing process. By tuning the thicknesses of the two layers, a series of coatings were prepared. These coatings were highly transparent and able to reduce reflectance. In addition, they adhered well to the substrate, and demonstrated superb antifogging capability on steam tests. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48822.     

排水泵线圈密封性能判定方法的研究

空调用排水泵使用环氧树脂对其线圈进行密封,且水泵长期工作在低温高湿的环境当中,环氧树脂亲水特性的优劣与水泵线圈的可靠性直接相关联,故如何快速判断水泵所用环氧树脂的亲水特性的优劣显得尤为重要。本研究根据环氧树脂的亲水特性,通过设计2 h、6 h、48 h、168 h四种时间梯度水煮实验,得出水煮时间的长短与水泵线圈重量、泄露电流、绝缘电阻关键参数的关联性关系,得出随着水煮时间的增加,水泵电气性能逐渐衰减的结论,创新提出利用水煮实验判断水泵线圈密封性优劣的新方法。     

城市公园亲水空间潜在安全隐患研究

本文以城市公园亲水空间的安全问题作为研究对象,从亲水空间景观元素的潜在安全隐患（物的不安全状态）和基于安全角度的游人环境行为（人的不安全行为）两个方面进行研究。并利用鱼刺图对城市公园亲水空间的潜在安全隐患进行了较为完整的梳理分析,最后提出了潜在安全隐患的消除途径。