Post and Prepolymerization Strategies to Develop Novel Photochromic Poly(esterimide)s Ewa Schab-Balcerzak, 1,2 Mariola Siwy, 1 Bozena Jarzabek, 1 Anna Kozanecka-Szmigiel, 3 Krzysztof Switkowski, 3 Bronislaw Pura 3 1 Centre of Polymer and Carbon Materials, Polish Academy of Sciences, 41-819 Zabrze, Poland 2 Institute of Chemistry, University of Silesia, 40-006 Katowice, Poland 3 Faculty of Physics, Warsaw University of Technology, 00-662 Warsaw, Poland Received 24 May 2010; accepted 14 August 2010 DOI 10.1002/app.33202 Published online 19 October 2010 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: This paper reports novel photoresponsive, processable poly(esterimide)s functionalized with the azo- benzene and tricyanovinylene groups. Post and prepoly- merization strategies were utilized for preparation of the new photochromic polymers with imide rings. The postpo- lymerization method of azopolymer synthesis included a functionalization of precursor poly(esterimide) containing dialkylaminophenyl groups with diazonium salt of aniline. The precursor poly(esterimide) was obtained from synthe- sized 2,2 0 [N-phenylethyloaniline-di(4-estro-1,2-dicarboxyli- c)]anhydride and 4,4 0 -methylene bis(2,6-dimethylaniline). The prepolymerization strategy based on polycondesation of 2,4-diaminoazobenzene with two dianhydrides, that is, with or without the azobenzene group. The new dianhydride with azobenzene unit was obtained. The reaction of post-tri- cyanovinylation was carried out for substitution of prepared polymers with tricyanovinylene groups. The synthesized polymers were characterized and evaluated by FTIR, 1 H NMR, X-ray, UV-Vis spectroscopies, and DSC. The polymers exhibited glass transition temperatures in the range of 119– 208  C and good solubilities in common organic solvents, pro- viding optical-quality films. Thermal stability of the polymers films was investigated by UV-Vis spectroscopy. Preliminary investigations of the optical anisotropy in chosen poly(esteri- mide)s were carried out by photoinduced birefringence meas- urements. Relatively high photoinduced birefringence (Dn ¼ 0.01) was measured for polyimide with covalently bonded azobenzene substituted with strong acceptor group. V C 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 631–643, 2011 Key words: polyimides; photochromic polymers; azoben- zene chromophores; photoinduced anisotropy INTRODUCTION Polymers are promising materials for applications in the fields of photonics and optoelectronics due to the advantage over inorganic crystals, such as good processability to form optical devices, high mechani- cal and dimensional stability, chemical resistance, low dielectric constants, and potentially large elec- trooptic coefficients. 1–3 Moreover, polymers have great flexibility in the range of polymer-chromo- phore combinations that can be selected to particular applications. To develop practical devices, the non- linear optical (NLO) polymer materials must fulfill many requirements including thermal, chemical and photochemical stability, low optical propagation losses, and mechanical properties for multilayer films processing. 4,5 One of the major challenges is to achieve the reasonable tradeoff among all these properties in a one sample. 6 For practical applica- tions, long-term chemical and orientational stabilities of polymeric NLO materials are required at the operating temperatures, which may vary between 80 and 125  C in dependence on the application. When polymeric materials are fabricated as electrooptic devices, they may also be exposed to temperatures of  200–250  C for a short period of time. 7 Several strategies have been suggested to achieve this goal. One approach is the utilization of high glass transi- tion temperature (T g ) polymers, such as polyimides, which have played a key role in the materials for the microelectronics, optics and aerospace industries due to their superior thermal stability, chemical resistance, and mechanical durability. 8 Moreover, polyimides are found to be promising candidates also because of their low dielectric constants, optical transparency, and compatibility with semiconductor device technol- ogy. 9–11 Polyimide derivatives have been attracting attention in the design of photochromic and second- order nonlinear optical polymers for improving the temporal stability of poled polymer films. 12–14 The chromophores can be introduced into poly- mers in two main ways: by dissolution in a polymer host (a guest-host system) and by covalent bonding of the chromophore to the macromolecular chain. It Correspondence to: E. Schab-Balcerzak (eschab-balcerzak@ cmpw-pan.edu.pl or ewa.schab-balcerzak@us.edu.pl). Journal of Applied Polymer Science, Vol. 120, 631–643 (2011) V C 2010 Wiley Periodicals, Inc.