芳叔胺-苄基氯引发甲基丙烯酸甲酯聚合的溶剂效应和取代基效应

N,N-二甲基苯胺-苄基氯(DMA-BzCl)体系引发甲基丙烯酸甲酯的初期聚合速率与溶剂的极性有关。在非质子性溶剂中,DMA苯环上的取代基将降低聚合速率;在质子性溶剂中,推电子基可加速反应,而吸电子基则相反。用DMA和Bzcl构成的季铵盐引发时,初期聚合速率与其浓度的平方根成正比,反应总表观活化能为71.5 kJ/mol。聚合物的紫外光谱证实,用DMA-BzCl混合物或其季铵盐引发时,聚合物大分子中含有DMA的残基。

Effects of solvents and substituents on the MMA polymerization initiated by the system of tertiary aromatic amines-benzyl chloride

The primary rate of the polymerization of methyl methacrylate (MMA) initiated by the mixture of N, N-dimethylaniline (DMA) and benzyl chloride (BzC1) was found to be affected notably by the polarity of the solvents used. In aprotic solvents, the sutstituent present on the benzene ring of DMA, no matter what origing it is, either an electrondonor or an accepter, will low the rate of polymerization more or less; however, in the case of protonic solvents, the rate will be enhanced by the substituents of an electron-donor, and vice versa. When the polymerization is initiated by a quaternary ammonium salt (I) composed of DMA and BzCl, its primary rate will vary with the square root of the concentration of I. The apparent overall activation energy of the reaction is 71.5 kJ/mol.Confirmed by the UV-analysis, the residual part of DMA was found joined to macromolecules proper of the polymers formed when the polymerization was initiated with DMA-BzCl or quaternary ammonium salt as mentioned.