Graft polymerization of vinyl acetate onto silica
Graft polymerization of vinyl acetate onto silica
复制标题
乙酸乙烯酯在二氧化硅上的接枝聚合
DOI：
--
复制
发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Y. Cohen
中科院分区：
文献类型：
--
作者：
V. Nguyẽ̂n;Wayne Yoshida;Y. Cohen
对无孔二氧化硅粒子与醋酸乙烯酯的自由基接枝聚合进行了实验研究。接枝过程包括用乙烯基三甲氧基硅烷进行表面活化，然后以偶氮二（2，4-二甲基戊腈）为引发剂在乙酸乙酯中进行自由基接枝聚合。初始单体浓度从10体积%变化到40体积%，并且反应跨越50 °C到70°C。所得的接枝聚合物，这是稳定的，在很宽的pH值范围内，由聚合物链的末端和共价键合到二氧化硅基板。实验聚合速率顺序，相对于单体浓度，范围从1.61到2.00，与高聚合制度的动力学顺序一致。聚合物接枝的相应速率顺序从1.24变化到1.43。聚合物接枝率随初始单体浓度和反应温度的升高而增加，且聚合物接枝表面随着聚合物接枝率的增加而变得更加疏水。本研究表明，较短链的更致密的接枝聚合物相在升高温度时产生。另一方面，聚合物链长和聚合物接枝密度都随着初始单体浓度的增加而增加。原子力显微镜确定的拓扑结构的聚合物接枝表面揭示了与预期的广泛的自由基聚合的分子量分布的表面簇和表面高程的分布。© 2002 Wiley Periodicals，Inc.应用聚合物科学杂志87：300-310，2003
The free-radical graft polymerization of vinyl acetate onto nonporous silica particles was studied experimentally. The grafting procedure consisted of surface activation with vinyltrimethoxysilane, followed by free-radical graft polymerization of vinyl acetate in ethyl acetate with 2,2′-azobis(2,4-dimethylpentanenitrile) initiator. Initial monomer concentration was varied from 10 to 40% by volume and the reaction was spanned from 50 to 70°C. The resulting grafted polymer, which was stable over a wide range of pH levels, consisted of polymer chains that are terminally and covalently bonded to the silica substrate. The experimental polymerization rate order, with respect to monomer concentration, ranged from 1.61 to 2.00, consistent with the kinetic order for the high polymerization regime. The corresponding rate order for polymer grafting varied from 1.24 to 1.43. The polymer graft yield increased with both initial monomer concentration and reaction temperature, and the polymer-grafted surface became more hydrophobic with increasing polymer graft yield. The present study suggests that a denser grafted polymer phase of shorter chains was created upon increasing temperature. On the other hand, both polymer chain length and polymer graft density increased with initial monomer concentration. Atomic force microscopy–determined topology of the polymer-grafted surface revealed a distribution of surface clusters and surface elevations consistent with the expected broad molecular-weight distribution for free-radical polymerization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 300–310, 2003