甲基丙烯酸甲酯的原子转移自由基悬浮聚合

以 1 苯基氯乙烷为引发剂 ,氯化亚铜为催化剂 ,2 ,2 联吡啶为配体 ,外加搅拌 ,氮气保护下进行了甲基丙烯酸甲酯 (MMA)在 80℃下的原子转移悬浮聚合 .结果表明 ,聚合反应符合对单体浓度为一级的动力学关系 .经计算聚合体系的增长自由基浓度为 5 .74× 10 - 8mol L .聚合物分子量随转化率呈线性增加 ,分子量分布较窄 ,Mw Mn 在 1.37～ 1.40之间 .还以AIBN为引发剂 ,在三氯化铁和三苯基膦存在下进行了MMA的反向原子转移本体和悬浮聚合研究 .结果证明本体聚合具有好的可控特征 ,分子量随转化率呈线性增长 ,分子量分布指数在 1.2 7～ 1.31之间 .聚合反应速率较快 ,聚合体系中的增长自由基浓度较高 ,为 1.6 4× 10 - 7mol L .而在此催化体系下的悬浮聚合则完全失去了活性特征

ATOM TRANSFER RADICAL SUSPENSION POLYMERIZATION OF METHYL METHACRYLATE

Atom transfer radical suspension polymerization (ATRP) of methyl methacrylate (MMA) was conducted at 80℃ using 1\|phenylethyl chloride (1\|PECl) as initiator,cuprous chloride(CuCl) as catalyst and 1,1\|bipyridine (Bpy) as ligand. The polymerization was carried out with a mechanical agitator under the protection of nitrogen atmosphere. In addition of the dispersing agent, NaCl was also used in the water phase to prevent the diffusion of the catalyst complex into water. The results show that the polymerization is a first order reaction with respect to monomer concentration. From the slop of the plot of lnM] 0/M] versus time, the concentration of the propagating radical was calculated as 5.74×10 -8 ?mol/L. The polymerization displayed living character as evidenced by a linear increase of molecular weight with conversion and a relatively narrow molecular weight distribution ( M w/ M n ranged from 1.37 to 1.40). Subsequently the reverse ATRP of MMA at 80℃ was conducted using AIBN as initiator, FeCl 3 and triphenylphosphine(PPh 3) as catalysts. The results indicate that the bulk polymerization demonstrated good control. The molecular weight increased with conversion and the M w/ M n ranged from 1.27 to 1.31. The polymerization rate is quite fast. The conversion approached to 75.6% after 2?h. From the linear plot of lnM] 0/M] versus time, the concentration of the growing radical was calculated as 1.64×10 -7 ?mol/L. However the suspension polymerization of MMA using this initiation\|catalyst system failed as evidenced by the large molecular weight (ca.100,000) and large value of M w/ M n(4.8～6.32).