Polymer Physics and Structure/Property Relationships of Thermally Stable Polyarylene Ethers for Second-Order Nonlinear Optics

This paper describes the structure/property relationships including the polymer backbone structures and molecular weight, chromophore/polymer interactions, and chromophore functionalization that influence the chromophore orientational dynamics and polymer relaxations in a special class of thermally stable polymers that was recently developed for second-order nonlinear optical applications. These poly(arylene ether) polymers (synthesis and characterization reported elsewhere) are being investigated because of their high glass transition temperatures (>200 °C), which may minimize the randomization of chromophore orientation following electric field poling. They also have hydrogen-bonding sites that can interact with the chromophores, which may improve the temporal stability of chromophore orientation following poling. Generalization of the observed polymer dynamics to other second-order nonlinear optical polymers is discussed. Second harmonic generation, a second-order nonlinear optical effect, and dielectric relaxation are the two techniques employed to examine the intermolecular cooperativity and segmental relaxation behavior in these polymers. By examination of the second-order nonlinear optical properties of the doped or functionalized polymeric material as a function of time and temperature and the dielectric relaxation phenomena as a function of frequency and temperature, information concerning the local mobility and relaxation phenomena of the polymer microenvironment surrounding the nonlinear optical chromophores can be obtained. The dielectric loss data were analyzed using the Havriliak−Negami empirical function and the Schonhals and Schlosser model to examine the extent of intermolecular coupling in these polymer systems. Results obtained using these two techniques are correlated.