Enhanced temporal stability of an NLO polyurethane via a two-dimensional chromophore

A new NLO-active polyurethane (T-g = 145 degreesC) based on a two-dimension al NLO chromophore has been investigated. Two ends of this lambda-shaped ch romophore can be directly bound to the main chain of polyurethane. After po ling, fast relaxation of the effective second harmonic (SH) coefficient was observed at temperatures higher than 122 degreesC. Moreover, excellent tem peratures higher than 122 degreesC. Moreover, excellent temporal stability at 100 degreesC was obtained despite the operating temperature being very c lose to the fast relaxation temperature. This is due to the fact that embed ding the rigid lambda-shaped chromophores into the polymer backbone effecti vely restricts molecular motion at temperatures close to T-g.