This study aimed at the synthesis of silica particles grafted with better-defined homopolymers and block copolymers by tandem approach.Z-functionalized Sbenzyl S’-(3-trimethoxysilyl)propyltrithiocarbonate(BTPT)was us...
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This study aimed at the synthesis of silica particles grafted with better-defined homopolymers and block copolymers by tandem approach.Z-functionalized Sbenzyl S’-(3-trimethoxysilyl)propyltrithiocarbonate(BTPT)was used as a couplable RAFT agent to synthesize the target inorganic-organic *** coupling reaction and RAFT process using silica particles and BTPT as raw materials efficiently afforded homopolymers grafted silica,and RAFTsynthesized macro chain transfer agents withω-terminal trimethoxysilane moiety were utilized to mediate graft reaction to prepare silica particles grafted with di-,tri-and tetrablock copolymers comprised of polymer segments such as polystyrene,polyacrylamides and *** the grafted chains had molecular weights ranging between 3920 and 24800 g/mol,the molar grafting ratios,which were dependent on reaction conditions and types and compositions of grafted chains,were estimated to be in the range of 15.2–101μmol/g,and grafted polymers usually had polydispersity indices lower than 1.3,revealing that the grafting process was almost *** the best of our knowledge,this versatile tandem approach is one of the most facile techniques to prepare silica particles grafted with polymeric chains with controlled molecular weight,low polydispersity and precise composition due to its minimal reaction steps,mild conditions,straightforward synthesis and satisfactory controllability.
Antibacterial polymers of dimethylaminoethyl methacrylate benzyl ammonium chloride（DMAEMA-BC） with various molecular weights（Mws） were prepared under controlling radical polymerization conditions. The Mws of these...
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Antibacterial polymers of dimethylaminoethyl methacrylate benzyl ammonium chloride（DMAEMA-BC） with various molecular weights（Mws） were prepared under controlling radical polymerization conditions. The Mws of these polymers were determined by means of static multiangle laser light scattering and viscosity method. A Mark-Houwink equation was established to be [η]=0.154M0.764 for the Mw evaluation of poly（DMAEMA-BC）s. The effects of the Mws of these poly（DMAEMA-BC）s on their antibacterial activities against E. coli and S. aureus were investigated by various methods including viable cell counting, electrical conductivity titration, intracellular constituent leakage tests and electron microscopy. Our results indicate that the antibacterial efficiency of DMAEMA-BC was significantly enhanced after the monomers were polymerized into a polymer and increased obviously with the Mws,as a result of the increase of charge density. Further investigation of the molecular basis underlying the anti-bacterial role of these polymers revealed that poly（DMAEMA-BC） promoted the release of potassium ion from the membrane of bacterial cells and the release increased significantly with the Mws of the polymers used.
4,4'-Biphenylene-silicas were prepared using the self-assemblies of a chiral low-molecular-weight amphiphile as templates,which exhibited chirality at both a nano and an angstrom *** CD spectra were simulated by t...
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4,4'-Biphenylene-silicas were prepared using the self-assemblies of a chiral low-molecular-weight amphiphile as templates,which exhibited chirality at both a nano and an angstrom *** CD spectra were simulated by the time-dependent density functional *** was found that the stacking and the twist of the biphenylene rings can be revealed from the first and second CD signals, *** chiral silicas have been widely developed,it is hard to know that they are chiral or not at angstrom *** on the result shown here,4,4'-bis(triethoxysilyl)-l,l'-biphenyl was used as a chiral sensor for ***,other UV active compounds with conformational chirality are proposed to be used as the chiral sensors for silicas and the other chiral materials.
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