长链聚酰亚胺的制备与表征

Synthesis and characterization of long-chain polyimides

以长链二胺4,4' 二(4 氨基苯氧基)二苯砜(BAPS)为单体,采用两步法分别与二酐PMDA、ODPA、BPADA合成了3种链长的聚酰亚胺。实验利用GPC监测0 05mol/L聚酰胺酸(PAA)的数均聚合度(Xn)及相对分子质量分布随缩聚时间的变化关系,结果表明该反应为一逐步缩聚反应,缩聚速率随二酐电子亲和性(EA)的递增而增加;与预聚体聚酰胺酸相比,热处理环化得到聚酰亚胺其数均分子质量( Mn)和特性粘度[η]均有所下降,而分布指数(D)增大。此外还利用红外光谱(FTIR)、差分扫描量热法(DSC)、热重分析(TGA)等对聚酰亚胺进行了表征,结果表明聚酰亚胺(PI)的玻璃化温度(tg)和热分解温度(td)随着聚合单元长度的增加而降低。

Three kinds of longchain polyimides had been prepared through the condensations of the longchain BAPS with PMDA,ODPA and BPADA, respectively. The changes of numberaverage degree of polymerization (Xn), molecular weight distribution of PAA versus time were investigated for 0.05 mol/L solution by the GPC. The results showed that it is a typical stepgrowth polymerization and the polymerization rate of PAA increased with the increase of electroaffinity of dianhydride. Compared with each other of those of PAA, the numberaverage molecular weight(n) and intrinsic viscosity of PI decreased while the width of molecular weight distribution increased. Moreover, FTIR,DSC and TGA were used to characterize PAA and PI. It was found that the glass transition temperature(Tg) and thermal stability of PI decreased with the increase of flexibility of dianhydrides and there were the characteristic bands of amic acid and imide in the infrared spectra of PAA and PI,respectively.