Radiation initiated synthesis,characterization, and swelling behavior of poly (acrylic acid-co-acrylamide)/starch grafted hydrogel

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.     

Effects of hydrolysis treatment on the structure and properties of semi-interpenetrating superabsorbent polymers

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.     

Ultrahigh molecular weight polyethylene with improved crosslink density,oxidation stability,and microbial inhibition by chemical crosslinking and tea polyphenols for total joint replacements

Highly crosslinked ultrahigh molecular weight polyethylene (UHMWPE) stabilized by vitamin E (VE) is widely applied in artificial joints as the bearings. Despite the approval, there is a discord that VE lowers the crosslinking efficiency, limiting its use at high concentration. In this work, we aim to obtain highly crosslinked and oxidation resistant UHMWPE through the conjunction of tea polyphenol and chemical crosslinking. We hypothesized that highly incorporated tea polyphenol with multiple reactive sites can ameliorate crosslinking efficiency of chemical crosslinked UHMWPE in comparison to VE. Epigallocatechin gallate (EGCG) as representative tea polyphenol was incorporated into UHMWPE at high concentration (2–8 wt%), followed by chemical crosslinking with 2 wt% organic peroxide. Unlike VE/UHMWPE blends as the control, chemical crosslinking achieved an increasing trend in crosslink density of EGCG/UHMWPE blends with increasing antioxidant concentration. High concentration of EGCG also enhanced the oxidation stability of UHMWPE. Intriguingly, EGCG endowed UHMWPE with an excellent antimicrobial property, which was inefficient in VE/UHMWPE. Cell viability was hardly affected by the high loaded antioxidant and peroxide. The chemically crosslinked UHMWPE blended with EGCG is proved to be a reasonable, cost effective and realistic alternative for use in artificial joints.     

Systematic investigation on the effect of crosslinking agent type and dosage on the performance of TPU/MVQ based thermoplastic vulcanizates

Dynamic vulcanized thermoplastic polyurethane (TPU)/methyl vinyl silicone rubber (MVQ) thermoplastic vulcanizates (TPVs) were prepared in torque rheometer. The influence of the type and amount of peroxide crosslinking agent on the mechanical properties, thermal stability, micromorphology and melt flowability was systematically investigated. The results showed that the mechanical properties of the TPVs vulcanized by 2,5-dimethyl-2,5-di (tert-butyl peroxy) hexane (DBPH) first increased and then decreased with increasing the peroxide amount, while for dicumyl peroxide (DCP) vulcanizing system the mechanical properties slowly increased. Besides, the comprehensive mechanical properties vulcanized by DBPH were better than those of DCP group. The results of the thermogravimetric analysis showed that the TPVs vulcanized by DBPH had better heat stability, corresponding to the excellent thermo-oxidative aging performance and the 38% increase in tensile strength after aging. In addition, the MVQ rubber particles showed better dispersing performance for DBPH vulcanizing system. The melt flow rate of the TPVs showed a linear relationship with increasing DBPH dosage and became worse after the amount of crosslinking agent exceeded 1.5 phr. By comprehensive comparison, the TPVs have better performance when use peroxide DBPH as the crosslinking agent and the dosage is 1.5 phr.     

氯化聚乙烯双亲性接枝聚合物的合成与表征（Ⅰ）

采用“架桥剂”法,以马来酸酐（ＭＡＮ）为“架桥剂”,使氯化聚乙烯（ＣＰＥ）主链上接上一定数量的酸酐基团,然后利用接上去的酸酐基团与ＰＭＭＡ－ＯＨ、ＰＥＧ、ＰＰＧ、ＰＴＭＧ等反应合成了主链疏水、支链亲水或疏水的双亲性聚合物,并用ＩＲ、ＴＧ－ＤＴＡ进行了表征。     

Multicolor Photo‐Crosslinkable AIEgens toward Compact Nanodots for Subcellular Imaging and STED Nanoscopy

Aggregation induced emission (AIE) has attracted considerable interest for the development of fluorescence probes. However, controlling the bioconjugation and cellular labeling of AIE dots is a challenging problem. Here, this study reports a general approach for preparing small and bioconjugated AIE dots for specific labeling of cellular targets. The strategy is based on the synthesis of oxetane‐substituted AIEgens to generate compact and ultrastable AIE dots via photo‐crosslinking. A small amount of polymer enriched with oxetane groups is cocondensed with most of the AIEgens to functionalize the nanodot surface for subsequent streptavidin bioconjugation. Due to their small sizes, good stability, and surface functionalization, the cell‐surface markers and subcellular structures are specifically labeled by the AIE dot bioconjugates. Remarkably, stimulated emission depletion imaging with AIE dots is achieved for the first time, and the spatial resolution is significantly enhanced to ≈95 nm. This study provides a general approach for small functional molecules for preparing small sized and ultrastable nanodots.     

TGDDM/DDS交联环氧树脂的分子动力学模拟

采用分子动力学(MD)模拟方法研究了环氧树脂4,4’-二氨基二苯甲烷四缩水甘油醚(TGDDM)与固化剂4,4’-二氨基二苯砜(DDS)交联过程中结构与能量的变化情况,预测了交联环氧树脂的玻璃化转变温度(Tg)、体积热膨胀系数和力学性能。研究结果表明,交联反应使得TGDDM/DDS体系密度增大,结构堆积更加紧密,范德华力和静电作用力增大,总能量减小,反应过程放热,通过温度-比体积曲线得到了交联体系的Tg约为527.9K,与实验值538.9K较为吻合,交联显著增强了材料的力学性能,而高温环境会引起树脂力学性能的下降,通过径向分布函数g(r)揭示了温度对交联环氧树脂结构的影响规律。     

挤出过程中交联聚氯乙烯的研究

应用过氧化二异丙苯 /苯乙烯 /三乙醇胺体系在挤出过程中实现了聚氯乙烯的一步交联 ,研究了三乙醇胺和过氧化二异丙苯用量对交联产物力学性能及交联凝胶率的影响。研究发现 ,三乙醇胺对PVC交联结构的形成具有明显的促进作用。在苯乙烯用量 5 phr,三乙醇胺用量为 0 33phr时 ,过氧化二异丙苯在 0 15phr取得最佳值 ;当苯乙烯用量 5 phr,过氧化二异丙苯用量 0 15 phr时 ,三乙醇胺用量在 0 4hpr取得最佳值。交联可以使聚合物材料的力学强度得到提高     

交联染料的研究进展

综述了交联染料的研究进展，主要介绍了Basazol、Indosol交联染料、氨烷基交联染料各自的结构特征、配套交联剂。在指出这类染料不足的同时，阐明了交联染料的发展方向。有13篇参考文献。     

交联型水性聚氨酯树脂的合成研究

用聚乙二醇和甲苯二异氰酸酯等进行预聚反应制备交联型水性聚氨酯树脂。系统地研究了nNCO／nOH(聚乙二醇)值对膜力学性能及玻璃化转变温度的影响，并考察了nNCO/nOH(总)值及交联剂三羟甲基丙烷的用量对乳液稳定性的影响。