甲基丙烯酸正丁酯正相微乳液可控/“活性”光聚合动力学研究

Control/Living Free Radical Photopolymerization of n-Butyl Methacrylate in O/W Microemulsion

以末端含溴原子的光引发剂2-溴异丁酰氧基-2-甲基-1-苯基甲酮(HMPP-Br)为引发剂,2,2,6,6-四甲基哌啶-1-氧自由基(TEMPO)和2,2,6,6-四甲基哌啶醇(TMP)为调控剂,采用光聚合方法研究了甲基丙烯酸正丁酯(n-BMA)/十二烷基硫酸钠(SDS)/水/正丁醇O/W型正相微乳液体系的光聚合反应动力学.结果表明,改性后的引发剂具有一定的引发活性,且聚合微乳液体系较稳定,聚合反应获得了良好的ln[M]0/[M]与时间、数均分子量与转化率之间的线性动力学关系,制备了分子量分布较窄的Poly(n-BMA)均聚物.

Using 2-bromo-（2-methyl-1-oxopropoxy）-2-methyl-propio-phenone（HMPP-Br） as a photoinitiator,the controlled/living photopolymerization of n-butyl methacrylate（n-BMA） mediated by 2,2,6,6-tetramethyl-piperidinyl-l-oxyl（TEMPO） and 2,2,6,6-tetramethyl-4-piperidinol（TMP） in the microemulsion of n-BMA/n-butanol/SDS-H2O system（O/W） was performed at ambient temperature.The controlling mechanism and reaction kinetics of controlled/living free radical photopolymerization of n-BMA in microemulsion was investigated.It was shown that the monomer conversion increased linearly with the increased exposure time,and the number-average molecular weight（Mn） of Poly（n-BMA） is increased linearly with the monomer conversion increasing under the condition with/=1.1,the content of initiator of 4.5%（mass fraction） and the irradiation intensity of 5.5 mW/cm2.The results show that when it was mediated by TEMPO/TMP,the photopolymerization of n-BMA in the microemulsion was to be kineticly controlled.It was found that the plots of number-average molecular weight vs.conversion and ln（[M]0/[M]） vs.time were liner respectively,and the n-BMA homopolymers exhibited relatively narrow molecular weight distributions（PDI=1.25—1.45）,even until the conversion was up.This shows that TEMPO combined with TMP used as a mediator was evidently available.