Synthesis and characterization of bi‐functional photorefractive hyperbranched polyisophthalesters

Abstract

AbstractA series of novel bi‐functional photorefractive (PR) hyperbranched polyisophthalesters (HPIPEs) with pendant end carbazolyl and azo groups, acting as photoconductors and electro‐optic (EO) chromophores, respectively, were synthesized by modifying the HPIPE with N‐hydroxyethyl carbazole and 4‐(p‐nitrophenylazo) (N‐ethoxyl‐N‐methyl)aniline. These obtained PR polymers were then characterized by UV‐vis and IR spectrum, 1H‐NMR, elemental analysis, gel permeation chromatography (GPC) measurements and thermal analysis. As expected, due to their three‐dimension molecular structures, the lower glass transition temperatures (21–49°C) were obtained in the absence of plasticizers, which provide a necessary free volume for the EO chromophores reorientation. The acceptable thermal stability, as well as the degradation temperatures of 205–260°C, was also determined by thermogravimetric analysis (TGA). The two‐beam coupling experiments of HPIPE‐25Azo theoretically containing 25% azo end groups showed that a high gain coefficient of 59 cm−1 was obtained at the applied electric field of 80 V μm−1. Copyright © 2004 John Wiley & Sons, Ltd.