| Benzothiazoles are well known for their use in high temperature applications, in particular thermally stable polymers. Here, novel difunctional nonlinear optical azobenzothiazole compounds with exceptional thermal stability have been synthesized for incorporation into cross-linked polymeric systems. A viable separation technique and thermal degradation profile has been established for the isomers (5'-nitro-6'-hydroxy-benzothiazoleazo)-[2-(N-ethyl-N-hydroxyethyl)]-aniline and (7'-nitro-6'-hydroxy-benzothiazoleazo)-[2-(N-ethyl-N-hydroxyethyl)]-aniline. The nonlinear optical response of the cross-linked polymers containing these azodyes will be studied with second-harmonic generation measurements in the future. A further objective of the research was to determine the optimum distance between nonlinear optical chromophores to maximize poling. For this study (2'methyl-4'-nitrophenylazo)-[N,N-bis(2-hydroxyethyl)]-aniline was synthesized and incorporated into side-chain polymeric systems with diisocyanate spacer groups that impart different local environments around the chromophore. The nonlinear optical response of these polymers have been studied with second-harmonic generation to identify the spacer or spacers that will provide the optimum separation and/or conformation between chromophores allowing poling efficiency to be maximized. The findings suggest that the more flexible the system the more efficient the poling process. Findings concerning the positive, negative, and specifics of the project and implications for future work are discussed. |
