高分子量聚丙烯腈的结构表征

Characterizing on the Structure of High Molecular Weight PAN Synthesized in DMSO/H_(2)O

丙烯腈与衣康酸在二甲基亚砜/水(DMSO/H2O)中聚合,合成了高分子量的聚丙烯腈.通过粘度测定、扫描电镜、红外光谱等对聚丙烯腈聚合物进行了表征.研究发现,含有衣康酸的高分子量聚丙烯腈聚合物具有高分子电解质所特有的现象:其稀溶液中,在浓度降低到某一点突然出现粘度迅速增加的现象.在反应介质DMSO/H2O中,随着DMSO组分的不断减少,聚合物的颗粒特性发生变化,由松软的块状到不规则的细粒状.聚丙烯腈均聚物的环化反应比较慢,而且难以形成环化的梯形聚合物结构.通过引入共聚单体,如衣康酸,使聚丙烯腈聚合物的氧化反应开始温度提前,同时还提高了聚丙烯腈聚合物的环化反应速率.

High molecular weight PAN is obtained by the free-radical suspension copolymerization of itaconic acid (IA) and acrylonitrile(AN) which is carried out in DMSO/H_(2)O by using AIBN as initiator. The structure and properties of PAN polymers are characterized by various means, such as intrinsic viscosity measurements, fourier transform infrared spectroscopy(FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), etc. Because of the inclusion of good solvent DMSO, the solution degree of AN in DMSO/H_(2)O is higher than that in water, the resultant copolymer pellets become porous and from soft bulk to solid grain with the decrease of DMSO content in DMSO/H_(2)O ratio. High molecular weight of P(AN-co-IA) copolymers have faster preoxidization and cyclization than that for PAN homopolymers at 220 ℃ resulted from the FT-IR study.