丙烯腈与衣康酸在混合溶剂中的共聚合研究

Study on copolymerization of acrylonitrile and itaconic acid in mixed solvent system

以二甲基亚砜(DMSO)和二甲基乙酰胺(DMAc)为混合溶剂,研究了丙烯腈(AN)与衣康酸(IA)的自由基共聚反应,通过红外光谱和元素分析仪等对聚合物的化学结构和组成进行了分析,并研究了DMAc的含量对单体转化率、相对分子质量及其分布的影响。结果表明:DMSO/DMAc混合溶剂所得聚丙烯腈(PAN)的化学结构与DMSO单一溶剂所得一致;随着DMAc含量的增加,PAN相对分子质量减小,相对分子质量分布逐渐增大;当DMAc溶剂质量分数小于5%时,单体转化率与使用DMSO单一溶剂时相当,且聚合物重均相对分子质量大于1.1×105,相对分子质量分布也较窄(小于3.0);DMAc的加入大大降低了PAN原液的黏度,且在低剪切速率下溶液接近牛顿流体;在DMSO中加入少量的DMAc作为混合溶剂进行PAN共聚合反应,可以减缓环化反应的作用。

The free radical copolymerization of acrylonitrile （AN） and itaconic acid （IA） was investigated in the mixed solvent system of dimethyl sulfoxide （DMSO） and dimethylacetamide （DMAc）. The chemical structure and composition of the polymers were analyzed by Fourier transform infrared spectroscopy （FTIR） and elemental analysis. The effect of DMAc content on the conersion ratio, relative molecular mass and relative molecular mass distribution was studied. The results showed that polyacrylonitrile （PAN） prepared in DMSO/DMAc mixed solvent possessed the same chemical structure as that prepared in DMSO single solvent ; the relative molecular mass of PAN was decreased and the relative molecular mass distribution was gradually increased with the increase of DMAc content ; the monomer conversion rate was equal to that in DMSO single solvent, the Weight-average molecular mass of the obtained polymer was above 1.1 ×10^5 and the relative molecular mass distribution was relatively narrow （ below 3.0） as the mass fraction of DMAc was less than 5% ; the addition of DMAc could considerably decrease the viscosity of PAN spinning solution and make the solution approach to non-Newtonian fluid at low sheafing rate ; and a small amount of DMAc incorporated into DMSO solvent system could depress the eyclization effect during the copolymerization of PAN.