以α-甲基苯乙烯(AMS)、马来酸酐(MANH)为共聚单体,偶氮二异丁腈(AIBN)为引发剂,采用自稳定沉淀聚合法合成了α-甲基苯乙烯和马来酸酐的共聚物,再将其皂化后得到具有引发和乳化双重作用的共聚物.该共聚物可以作为大分子引发剂再引发甲基丙烯酸甲酯(MMA)进行无皂乳液聚合.采用扫描电镜、红外光谱仪、乌氏黏度计等仪器对AMS-MANH共聚物以及乳液聚合产物进行了表征.结果表明,乳液聚合产物是以PMMA为主长链,AMS和MANH低聚物为短链的嵌段共聚物.单体最高转化率可达到85%,特性黏数在80 mL/g左右.乳胶粒子粒径在150~200 nm之间.聚合速率随着引发剂浓度的增加而增大,聚合物的特性黏数随着转化率的提高基本呈线性增大.
The copolymer of a-methyl styrene (AMS) and maleic anhydride (MANH) was synthesized by self-stable precipitation polymerization. The resulting AMS-MANH eopolymer was saponified and then served as macroinitiator and emulsifier for the further surfactant-free polymerization of methyl methacrylate (MMA). Surfaetant-free emulsion polymerization of MMA was carried at 90~C. The AMS-MANH copolymer and the obtained block-eopolymer were characterized by Fourier transform infrared spectroscopy (FTIR) , nuclear magnetic resonance (NMR) , gel permeation chromatography (GPC) and scanning electron microscopy (SEM). The results showed that the surfactant-free polymerization of MMA can be carried out by using saponified AMS-MANH copolymer,without any other initiator and emulsifier. Based on FTIR and t H-NMR,the emulsion polymerization product was block copolymer of PMMA and AMS-MANH copolymer. During the process of surfactant-free polymerization of MMA,the polymerization rate increased along with the increasing of the concentration of maeroinitiator. The maximum of polymerization conversion was 85% and the particle sizes ranged from 150 nm to 200 nm. The intrinsic viscosity number of the copolymer was about 80 mL/g. In addition,the intrinsic viscosity numbers of copolymers increased linearly with the rising of polymerization conversion. Based on the research results,a possible reaction mechanism has been proposed. This novel method is expected to be applied to other kinds of monomers.