苯乙烯和甲基丙烯酸甲酯梯度共聚物的合成

Synthesis of styrene/methyl methacrylate gradient copolymer

以 2－溴异丁酸乙酯为引发剂，溴化亚铜 /联二吡啶 /铜为催化剂，通过原子转移自由基聚合 (ATRP)以及连续补加第二单体的方法制备苯乙烯 (St)－甲基丙烯酸甲酯 (MMA)梯度共聚物。共聚物相对分子质量的可控性和窄分布证明这是一种活性聚合过程；反应过程中聚合物链的组成变化情况说明形成了梯度结构；聚合温度和 MMA加料速度影响聚合速率和共聚物梯度结构，聚合温度升高和加料速度增大使聚合速率加快；改变单体与引发剂的配比，可以得到相应的相对分子质量聚合物。

The gradient copolymer of styrene (St) - methyl methacrylate(MMA) via addition of MMA as a second monomer was prepared by atom transfer radical polymerization (ATRP) at 110 °C promoted by Eib - Br/CuBr/bpy. Controlled relative molecular mass and narrow relative molecular mass distributions proved that the copolymerizations had obvious 'living' characteristics. The unremitting change of copolymer composition through the copolymerization proved that gradient structure was formed. Copolymerization rate and copolymer structure could be influced by copolymerization temperature and addition rate of MMA. Copolymerization rate increased when copolymerization temperature rose or MMA addition rate grew. The relative molecular mass of P(St-t-MMA) could be controlled by the mole ratio of St/Eib-Br.