含不同发色团聚氨酯的二阶非线性光学性质

Comparison of non - linear optical properties of polyurethanes containing different chromophore groups

合成了含不同分子超极化系数(β)的发色团作为侧基的4种聚氨酯,研究了它们的二阶非线性光学(NLO)性质。由甲苯-2,4-二异氰酸酯(TDI)分别与含偶氮苯(分散红DR-19)、偶氮苯并噻唑或双偶氮苯化合物反应,制备了U-1,U-3,U-4;U-2则通过六亚甲基-1,6-二异氰酸酯与DR-19反应而得。通过旋转涂膜及加热电晕极化制得透明极化聚氨酯薄膜。经DSC删定,试样玻璃化转变温度(Tg)依下列顺序递减:U-2,U-1或U-4,U-3。所有极化聚氨酯膜的二阶非线性光学系数(X2)达到10-7esu,并按以下顺序递减:U-4,U-3,U-2,U-1。这主要依赖于发色团的β,发色团的β愈高,聚氨酯的X2愈大。NLO性质的稳定性随聚氨酯的Tg提高而增加。U-2极化膜的稳定性最好,在120℃经400h,序参数可保持98%。

Polyurethanes containing azo chromophore groups with different hyperpolarizability(β) as side chains were synthesized and their second - order non - linear ( NLO ) properties were studied. U - 1 ,U - 3 and U - 4 were prepared from the reaction of toluene 2,4 - diisocyanate with N, N - di (2 - hydroxyethyl) aniline containing azobenzene ( DR -19), azo - benzothiazole and bisazobenzene, respectively, whereas U - 2 were synthesized from the reaction of hexam-ethylene 1,6 - diisocyanate with DR - 19. Thin transparent poled film of polynrethanes were prepared by spin - coating, followed by thermal corona poling. Glass transition tempera-tures(Tg) decreased in the order : U -2 , U - 1 ( U-4 ), U -3. The second - order NLO coefficient of all the poled films Can reached 10 esu and decreased in the order: U -4, U-3,U-2,U - 1. which depended mainly on β of the chromophore groups. The higher the β value, the larger NLO coefficient of the poled film. The temporal stability of NLO properties for the four polynrethanes increased with the Tg. The poled U - 2 film showed the best stability and maintained 98% of the order parameter at 120℃ for more than 400 h.