分子印迹聚合物负载纳米金催化剂的制备及其底物识别性能

以4-硝基苯甲醇与氯金酸的络合物为模板,利用聚合物空腔内胺基捕获NaBH4还原的纳米粒子,设计和制备了一种具有底物识别性能的分子印迹聚合物负载纳米Au催化剂(Au/MIP).运用红外光谱、紫外-可见光谱和扫描电镜等方法对催化剂进行了表征.同时以水为溶剂,过氧化氢为氧化剂,考察了催化剂在取代苯甲醇氧化反应中的催化性能.结...     

One‐pot synthesis of hyperbranched glycopolymers by RAFT polymerization

Soluble hyperbranched glycopolymers were prepared by copolymerization of glycan monomers with reversible addition‐fragmentation chain transfer polymerization (RAFT) inimers in a simple one‐pot reaction. Two novel RAFT inimers, 2‐(methacryloyloxy)ethyl 4‐cyano‐4‐(phenylcarbonothioylthio)pentanoate (MAE‐CPP) and 2‐(3‐(benzylthiocarbonothioylthio)propanoyloxy)ethyl acrylate (BCP‐EA) were synthesized and used to prepare hyperbranched glycopolymers. Two types of galactose‐based saccharide monomers, 6‐O‐methacryloyl‐1,2:3,4‐di‐O‐isopropylidene‐D ‐galactopyranose (proGal‐M) and 6‐O‐(2′‐acrylamido‐2′‐methylpropanoate)‐1,2:3,4‐di‐O‐isopropylidene‐D ‐galactopyranose (proGal‐A), containing a methacrylate and an acrylamide group, respectively, were also synthesized and polymerized under the mediation of the MAE‐CPP and BCP‐EA inimers, respectively. In addition, hyperbranched poly(proGal‐M), linear poly(proGal‐A), and hyperbranched poly(proGal‐A) were generated and their polymerization kinetics were studied and compared. An unexpected difference was observed in the kinetics between the two monomers during polymerization: the relationship between polymerization rate and concentration of inimer was totally opposite in the two monomer–inimer systems. Branching analysis was conducted by using degree of branching (DB) as the measurement parameter. As expected, a higher DB occurred with increased inimer content. Furthermore, these polymers were readily deprotected by hydrolysis in trifluoroacetic acid solution resulting in water‐soluble polymers. The resulting branched glycopolymers have potential as biomimetics of polysaccharides. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

A STUDY OF CRACK CLOSURE IN ELECTRIC-FIELD-INDUCED FATIGUE IN FERROELECTRIC CERAMICS

Considering the influence of the domain switching near the tip of a crack and apply-ing the idea of multiscale singularity fields in piezoelectric fracture,we have obtained an empiricalcriterion for the crack closure.Based on the domain switching in the electric yield region,referringto Yang's results on the small scale yield model for the electrical fatigue crack,a model of thecrack closure during electric-field-induced fatigue is developed to analyze the crack growth.Interms of the model we have obtained the formula of the rate of the crack growth under cyclicelectric loading.Finally we compare the theoretical predictions with the results given by Cao andEvans experimentally.It should be pointed out that the model proposed is empirical and needsto be verified by more experimental results.     

Nanocellulose based hydrogel or aerogel scaffolds for tissue engineering

Cellulose - Some structures and properties of hydrogel or aerogel tissue engineering scaffolds can be regulated by adding nanocellulose due to its biocompatibility, biodegradability, hydrophilic...