阳离子-原子转移自由基顺序聚合合成异丁烯-p-甲基苯乙烯接枝丙烯酸叔丁酯共聚物

以酰基化试剂α-溴代丙酰溴对异丁烯和对甲基苯乙烯的二元共聚物中的p-甲基苯乙烯单元进行Friedel-Crafts酰基化取代反应，获得大分子引发剂。以所得大分子引发剂引发丙烯酸叔丁酯的原子转移自由基聚合制得了梳状异丁烯-p-甲基苯乙烯接枝丙烯酸叔丁酯共聚物。所得产物用FTIR、¹H NMR、¹³C-NMR和GPC等进行了表征，结果表明, 二元共聚物的数均分子量约为25000，分子量分布约为2.18，其中p-甲基苯乙烯的摩尔分数约为5%～8%；共聚物的酰基化取代度可达83%；所得丙烯酸叔丁酯接枝共聚物的数均分子量可到58800，分子量分布约为2.26。

Synthesis of poly (isobutyl-p-methylstyrene-g-tert-butyl acrylate) by combination of cationic polymerization and ATRP in CH2Cl2 solution

Poly(isobutylene-p-methylstyrene-g-tert-butyl acrylate) P(IB-co-pMS-g-tBA)] was synthesized by the sequential cationic polymerization in solution CH₂Cl₂ and ATRP. The procedure consists of three steps: firstly, the random copolymer of poly (isobutyl-p-methylstyrene) P(IB-co-pMS)] was synthesized through a cationic polymerization; then, the unit of p-methylstyrene in the above copolymer was subjected to an electrophilic substitution reaction with α-bromopropionyl bromide as an acylating agent and aluminum chloride as a catalyst; and finally, the resulted acylated copolymer P(IB-co-pMS-CO-CHBr-CH₃) (M_w=28000, M_w/M_n=2.12) was employed as a macroinitiator, together with CuBr and N, N, N’, N’N”-pentamethyl diethylenetriamine (PMDETA), to initiate the ATRP of tert-butyl acrylate. The substitution degree of α-bromopropionyl groups in P(IB-co-pMS) was determined to be 83%, according to the integral height of phenyl protons and that of the corresponding proton in -CHBr-group. Characterization of copolymers was conducted by FTIR, ¹H-NMR, ¹³C-NMR and GPC measurements. The molecular weight (M_n) and its dispersity (M_w/M_n) of the graft copolymer P(IB-co-pMS-g-tBA)] was 58800 and 2.26.