Epoxy-Based Nonlinear Optical Polymers from Post Azo Coupling Reaction

A series of novel second-order nonlinear optical (NLO) polymers have been developed based on a precursor polymer prepared from the diglycidyl ether of Bisphenol A and aniline. The precursor polymer was postfunctionalized by azo coupling reaction and tricyanovinylation to form a number of NLO polymers with different conjugation lengths and electron acceptors. Post azo coupling reaction enabled the introduction of chromophores and extension of the conjugation lengths of the chromophores to take place in a single-step reaction. The chromophores introduced in the polymer system through covalent bonding not only define the NLO properties but also significantly modify other physical properties of the polymers. In this work, the correlation between chromophore structure and NLO polymer properties was extensively studied and the knowledge base was used to optimize polymer properties at the same time. The d 33 value of 66 pm/V at 1.542 μm was determined for a representative polymer of the class containing tricyanovinyl azo chromophores. The NLO properties of these polymers exhibit long-term stability at 80 °C.