用红外光谱研究甲基丙烯酸甲酯-苯乙烯共聚物序列结构

<正> 用高分辨核磁共振氢谱(H~1-NMR)研究聚甲基丙烯酸甲酯与苯乙烯共聚物(MMA-St共聚物)序列结构的文献很多.主要根据MMA-St共聚物中甲基丙烯酸甲酯的甲氧基共振峰,在H~1-NMR谱中呈现三重峰,这与MMA单元的近邻苯乙烯以及MMA与St的立体构型有关,借助于共聚理论可以间接求出包括立体构型影响在内的序列分布.用红外光谱(I.R)研究MMA-St共聚物的报道不多,柳(氵尺)一生用红外光谱研究了游离基聚合的St共聚物,其中包括MMA-St共聚物,观察到St单元的1068、543厘米~(-1)吸收峰随St序列长度缩短向高波数位移,此外MMA单元的1148、1191厘米~(-1)吸收峰,亦随MMA序列长度的改变有位移.我们的实验证实了柳(氵尺)一生的结果,同时还得到:

STUDY ON THE SEQUENCE STRUCTURE OF METHYL METHACRYLATE-STYRENE (M-S) COPOLYMERS BY INFRARED SPECTROSCOPY

A series of M-S low conversion copolymers were prepared by free radical polymerization and their IR spectra were measured.The 1149.5 cm-1 band which is related to a skeletal vibration coupled with CH deformation vibration in PMMA, is shifted to lower wave number with a decrease in the content of MMA in the copolymer.Two results can be drawn:(1) The correlation curve between this band position and the sequence length of M unit in the copolymer is obtained.(2) The displacement of wave number of this band is approximately propop-tional to F_SMS which is defined as the mole fraction of SMS in trids of SMS.MMS.SMM.and MMM. Other environmental-sensitive bands which depend on sequence distribution were also discussed.