官能化度对环氧树脂类偶氮聚合物光致取向的影响

INFLUENCE OF DEGREE OF FUNCTIONALIZATION ON THE PHOTOINDUCED ORIENTATION OF EPOXY-BASED AZO POLYMERS

利用光诱导双折射和偏振红外光谱法研究了偶氮官能化度对环氧树脂类偶氮聚合物BP-AZ-CA的光致取向行为的影响,重点研究了偶氮官能化度对偶氮生色团和聚合物主链的光致取向速度及饱和取向程度的影响规律.结果表明,随着偶氮官能化度的增加,偶氮生色团和聚合物主链的光致取向速度均降低,但二者的饱和取向程度增加.体系中氢键相互作用的增强是导致BP-AZ-CA的光致取向行为随偶氮官能化度增加而变化的原因之一.

This investigation studied the orientation behavior of one kind of epoxy-based azo polymers （BP- AZ-CA） containing carboxyl as the electron-withdrawing group on the azobenzene unit with different degree of functionalization （DF）. The orientation behavior was studied by photoinduced birefringence measurements and polarized infrared spectroscopy. The effect of degree of functionalizaiton on the orientation behavior of azo chromophores and polymer main-chains of BP-AZ-CA were observed. The results show that the orientation rate, relaxation rate and saturated orientation level of BP-AZ-CA are significantly influenced by the degree of functionalization. With the increase of DF of BP-AZ-CA, the orientation rate of both azo chromophores and polymer main-chains decrease. The influence of the DF on the orientation rate of polymer main-chains becomes weak when the DF of BP-AZ-CA is higher than 69%. With the increase of DF of BP-AZ-CA, the relaxation rate of both azo chromophores and polymer main-chains decrease, indicating the increasing molecular interaction has positive impact on the stability of the orientation of BP-AZ-CA induced by exciting polarized laser. The saturated orientation level of azo chromophores and polymer main-chains increases with the DF increase, but the DF has a more significant influence on azo chromophores than on polymer main-chains. The hydrogen-bond strength also plays an important role in enhancing the orientation behavior of BP-AZ-CA, increasing with the increase of DF.