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 d33 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.

Two types of new nonlinear optical polymers have been synthesized by postreaction of an epoxy-based polymer prepared from the diglycidyl ether of bisphenol A and aniline. The new polymers DGEBA-AZO-TCV and DGEBA-AN-TCV were synthesized by azo coupling of the epoxy polymer with 4-(tricyanovinyl)aniline and by reacting the epoxy polymer with tetracyanoethylene, respectively. Using an azo coupling reaction to functionalize the polymer allows introduction of the tricyanovinyl (TCV) group and extension of the conjugation length to take place in a single-step reaction. In both synthetic routes, TCV groups are introduced at the last stage of the polymer preparation, thus preventing the exposure of the TCV chromophores to harsh reaction conditions. The d 33 values for polymers DGEBA-AN-TCV and DGEBA-AZO-TCV were determined to be 27 and 66 pm/V at 1.542 μm, respectively, after corona poling. The two polymers retained 65% and 83% of the initial d 33 values after they had been heated at 80 °C for 1000 h.

ABSTRACT:A new organic/inorganic coating material based on the modification of a conventional melamine/polyol system has been developed. Polyhydroxyethylmethacrylate functionalized with alkoxysilane group was mixed with hexamethoxymethylmelamine. Upon heating under an acid catalyzed condition, both sol-gel reaction and melamine/polyol reactions occurred simultaneously, leading to highly crosslinked hybrid composites. The synthesis and characterization of the hybrid materials are reported. The organic/inorganic material was also coated and cured on polycarbonate substrates. The coated/cured samples exhibited excellent optical property. Surface scratch and abrasion resistance of the samples was found better than those of pristine polycarbonate substrate.

There has been a tremendous recent interest in the development of second‐order nonlinear optical (NLO) polymeric materials for photonic applications. However, a major drawback of second‐order NLO polymers that prevents them from being used in device applications is the instability of their electric field induced dipolar alignment. The randomization of the dipole orientation leads to the decay of second‐order optical nonlinearities. Numerous efforts have been made to increase the stability of the second‐order NLO properties of polymers. The search for new approaches to develop NLO polymers with optimal properties has been an active research area since the past decade. A novel approach, combining the hybrid properties of high glass transition temperatures, extensively extensively crosslinked networks and permanent entanglements, based on interpenetrating polymer networks (IPN) is introduced to develop stable second‐order NLO materials. Two types of IPN systems are prepared and their properties are investigated. The designing criteria and the rationale for the selection of polymers are discussed. The IPN samples show excellent temporal stability at elevated temperatures. Long‐term stability of the optical nonlinearity at 100°C has been observed in these materials. Temporal stability of the NLO properties of these IPNs is synergistically enhanced. Relaxation behavior of the optical nonlinearity of an IPN system has been studied and compared with that of a typical guest/host system. The improved temporal stability of the second‐order NLO properties of this IPN system is a result of the combination of the high rigidity of the polymer backbones, crosslinked matrices and permanent entanglements of the polymer networks. A slight modification of the chemical structure resulted in an improvement of the optical quality of the sample.

A new class of IPN system has been prepared and investigated. This IPN system combines the polybismaleinimide network and the NLO-active phenoxysilicon network. The second-order NLO coefficients, d33, values of the samples range from 2.5 to 6.7 pm/V depending on the composition and the processing conditions. The temporal stability of the second-order nonlinearities for these samples at 110 °C varies from 47 to 88 % retention after 274 h.