非线性光学环氧聚合物的近程结构对二次谐波产生弛豫特性的影响

Effects of the Short-Range Structure on Second Harmonic Generation Relaxation Behavior in Nonlinear Optical Epoxy Polymers

设计合成了三种具有不同主链化学结构的二阶非线性光学功能化环氧聚合物，并对其化学结构进行了表征，考察了聚合物近程结构对材料极化后二次谐波产生弛豫特性的影响。极化后线型聚合物链节的扭转弹性回复是二次谐波产生弛豫的主要原因，在温度处于Ｔｇ 以下或Ｔｇ 附近时玻璃化转变温度的高低决定了二次谐波产生弛豫的快慢；聚合物交联后有助于提高二次谐波产生的稳定性，但此时聚合物单个链节结构的柔顺性成为影响二次谐波产生弛豫的主要原因，刚性越大，材料将具有更稳定的二次谐波产生性能。极化聚合物的二次谐波产生弛豫过程非常复杂，需要综合考虑聚合物材料的近程和远程结构因素。

Three second-order nonlinear optical epoxy polymers with different main-chain structure were synthesized and characterized. The effects of polymer short-range structure, such as the chemical structure of polymer chain segment and crosslinking, were studied with second harmonic generation (SHG) decay, which are mainly characterized by the elastic recovery of polymer chain after poling. Below or near the glass transition temperature T g of polymers, the decay rate of SHG signal is determined mainly by the polymer's T g and crosslinking can improve the SHG stability. Moreover, the SHG decay rate was mainly determined by the flexibility of polymer chain segment rather than the polymer's T g after crosslinking in our experiments.