Chitin and chitosan in selected biomedical applications

Chitin (CT), the well-known natural biopolymer and chitosan (CS) (bio-based or “artificial polymer”) are non-toxic, biodegradable and biocompatible in nature. The advantages of these biomaterials are such that, they can be easily processed into different forms such as membranes, sponges, gels, scaffolds, microparticles, nanoparticles and nanofibers for a variety of biomedical applications such as drug delivery, gene therapy, tissue engineering and wound healing. Present review focuses on the diverse applications of CT and CS membranes and scaffolds for drug delivery, tissue engineering and targeted regenerative medicine. The chitinous scaffolds of marine sponges’ origin are discussed here for the first time. These CT based scaffolds obtained from Porifera possess remarkable and unique properties such as hydration, interconnected channels and diverse structural architecture. This review will provide a brief overview of CT and CS membranes and scaffolds toward different kinds of delivery applications such as anticancer drug delivery, osteogenic drug delivery, and growth factor delivery, because of their inimitable release behavior, degradation profile, mucoadhesive nature, etc. The review also provides an overview of the key features of CT and CS membranes and scaffolds such as their biodegradability, cytocompatibility and mechanical properties toward applications in tissue engineering and wound healing.     

不对称Gemini化合物的合成和性能研究

以环氧氯丙烷,N,N-二甲基十四烷基叔胺和咪唑为原料,合成了一种含咪唑环和十四烷基的不对称双季铵盐,通过IR以及元素分析对该化合物进行了结构表征,探索了其缓蚀性能和表面性能。结果表明,该化合物在50℃的5%H2SO4+0.1 mol/L NaCl溶液中投加量为70 mg/L时,对A3钢的缓蚀率达83%;在25℃下,其临界胶束浓度(CMC)为1.8×10-3 mol/L,低于DTAB,并且杀菌性能优于1227。因此,该化合物是一种高效的缓蚀杀菌剂。     

我国环氧氯丙烷市场趋势探讨

通过对我国环氧氯丙烷市场的供应、需求分析,指出了其未来的发展趋势,并由此得出我国环氧氯丙烷行业未来发展的建议。     

甲基丙烯酸缩水甘油酯的合成

甲基丙烯酸甲酯和甲醇反应得到甲基丙烯酸钾,和环氧氯丙烷（ECH）反应,合成了甲基丙烯酸缩水甘油酯。考察了催化剂选择、反应温度、反应时间、物料配比、催化剂用量等因素对反应的影响。结果表明,较佳的反应条件为：十六烷基三甲基溴化铵为催化剂,反应温度1100C,反应时间4h,n（甲基丙烯酸钾）：n（ECH）：1：7,催化剂用量0．2g。在此条件下,产品收率可达79％,含量大于98％。     

甘油环化法环氧氯丙烷发展现状

介绍了国内外甘油环化法环氧氯丙烷最新的项目建设动态。     

Pigment dyeing of polyamide‐epichlorohydrin cationized cotton fabrics

A synthesized cationic reagent named polyamide‐epichlorohydrin (PAE) was used to cationize cotton fabrics which were dyed with nanoscale pigments after PAE modification. The results showed that when the PAE concentration was below 7% (owf), the K/S value increased nearly linearly with increasing of PAE concentration, and excess that concentration the K/S value did not increase further. With increasing the pH value of cationization bath, the K/S value increased first and then decreased, the maximum K/S value appeared at pH 9–10. Cotton fabrics cationized at 80°C for 20 min exhibited the best cationizing result. Both the pigment uptake and the color strength reached their own maximum values when the dye bath was neutral. When the pigment concentration was 1% (owf) the addition of 1g/L sodium chloride in the dye bath could decrease the pigment uptake while for 5% (owf) pigment concentration the uptake increased with increasing the amount of sodium chloride. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Characterization and application of grafted polypropylene and polystyrene treated with epichlorohydrin coupled with cellulose or starch for immobilization processes

The direct‐irradiation‐induced grafting of acrylamide onto polypropylene films and polystyrene films with crosslinking epichlorohydrin (Epi) as a spacer was studied. The reaction of polyamide–Epi with cellulose and starch was carried out. Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis were carried out before and after the enzyme was immobilized to confirm the characterization of the polymer and the α‐amylase enzyme‐immobilized one. The physicochemical parameters of the immobilized enzymes were measured, and the kinetics of the coenzyme–polymer‐catalyzed reactions and stability were investigated. A direct comparison was made between the activities of the free and immobilized preparations. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

TS-1分子筛膜合成及其催化氯丙烯环氧化性能

Titanium silicalite-1 (TS-1) iflms were synthesized on stainless steel plate, glass slide and monolith supports via an in-situ hydrothermal method. Characterization data showed that the formation of TS...     

烷基化改性针叶木纤维制备热塑性材料的研究

以针叶木纤维为原料,先通过机械分丝处理、再采用烷基化改性制备出具有低玻璃化转变温度的新型烷基化纤维功能材料.通过红外光谱(IR)、扫描电镜(SEM)、X射线衍射(XRD)、热重(TG)和差示量热扫描(DSC)等对烷基化纤维的结构和物理性能进行了表征.结果表明,针叶木纤维表面的大量羟基能够被环氧氯丙烷中的甲基环氧基取代,表面形貌呈现粘流态.XRD分析表明,改性纤维分子链间隙变大,结晶度下降至21.4%.热分析显示,改性纤维的热塑性提高,玻璃化转变温度为137℃.     

Improvement of the phase-transfer catalysis method for synthesis of glycidyl ether

A convenient procedure for the synthesis of aliphatic alkylglycidyl ether has been studied. It has been found that the improved preparation of the alkylglycidyl ether can be achieved by using fatty alcohol such as octanol and octadecanol with epichlorohydrin in the presence of phase-transfer catalyst (PTC) such as 1-alkyloxypropan-2-ol-3-trimethyl ammonium methylsulfate, 1-alkyloxypropan-2-ol-3-methyldiethanolammonium methylsulfate, alkyloxy-2-hydroxypropyldimethylamine and alkyloxy-2-hydroxypropyldiethanolamine, tetrabutylammonium bromide, etc. without water and other organic solvents. This method, carried out in solid phase/organic phase (reactants and product themselves), has the following merits: (i) producing the solid by-products such as sodium chloride and sodium hydroxide which are easily removed by simple filtration, (ii) saving the amount of reactants used such as sodium chloride and phase-transfer catalyst, and (iii) increasing the yields of glycidyl ethers. The yields of octylglycidyl ether and octadecylglycidyl ether are 92.0 and 91.7%, respectively. The amount of sodium hydroxide used can be saved by from 1.5 to 0.7 molar ratio with respect to octanol in comparison with those in the conventional method using PTC.