氢氧根对苯乙烯和甲基丙烯酸甲酯ATRP悬浮共聚的影响

Influences of Hydroxyl Anion on Atom Transfer Radical Suspension Copolymerization of Styrene and Methyl Methacrylate

在85℃下,以α-溴异丁酰溴为引发剂、氯化亚铜为催化剂、2,2′-联吡啶(bpy)为配体,研究了氢氧化钠(NaOH)含量对苯乙烯和甲基丙烯酸甲酯的原子转移自由基悬浮共聚合的影响。1H-NMR分析和共聚竞聚率(rSt=0.83,rMMA=0.82)表明St/MMA原子转移悬浮共聚容易形成恒比共聚。ATRP的悬浮聚合表现出较好的可控/活性特征。在试验水相中氢氧根浓度为0至3%的范围内,单体转化率、ln[M]0/[M]和表观反应速率常数kappp都随着氢氧根浓度增大而增大。氢氧根并不影响聚合反应的一级动力学特征,但具有加速St/MMA原子转移悬浮共聚反应的作用。探讨了氢氧根在St/MMA原子转移悬浮共聚反应中的作用机理。

Atom transfer radical suspension copolymerization were carried out to synthesize Poly （styrene-methyl methacrylate） copolymer beads at the temperature of 85℃ using α-bromoisobutyryl bromide as initiator, cuprous chloride as catalyst and 2, 2＇-bipyridine as ligand, and effects of hydroxyl anion on the atom transfer radical suspension copolymerization were studied. Analysis of 1H-NMR and reactivity ratio （ rSt = 0.83, rMMA = 0.82 ） indicated that atom transfer radical copolymerization was easily to form nearly azeotropic copolymers. Atom transfer radical suspension copolymerization displayed controlled/living character as evidenced by the linear plot of In[ M ]0/ [M] versus time. Within the testing hydroxyl anion concentration from 0 to 3 % in the water phase, monomer conversion, In[ M]o/[ M] and the apparent reaction rate constant kp^app all increased with the increase of hydroxyl anion concentration. Hydroxyl anion did not alter first order kinetics character; it only promoted atom transfer radical suspension copolymerization, The mechanism of hydroxyl anion in atom transfer radical suspension copolymerization was analyzed in the paper.