Synthesis and characterization of thermally stable modular high-glass transition temperature second-order polymeric nonlinear optical materials

摘要

A comprehensive study of chromophore incorporation, chromophore-matrix stability, nonlinear optical (NLO) characteristics, and materials processing is described for the chromophore, (S)-(+)-N- (p-(4-nitrostyryl)phenyl) prolinol (NSP), appended to the glassy polymer, poly(p-hydroxystyrene) (PHS). Primary issues are: (i) defining chromophore functionalization level limitations, (ii) maximizing matrix-bound chromophore nonlinear response, (iii) maximizing the temporal stability of the electric field-induced acentric chromophore/matrix microstructure, and (iv) understanding thermal/oxidative stability of the chromophore/matrix. The chromophore functionalization level varied from 13% to 81%, resulting in a dramatic increase in corona-poled second-order nonlinear response, $chisp{(2)},$ from $5 times 10sp{-9}$ esu to $2.01times 1sp{-7}$ esu ($lambdasb0 = 1.064 mu$m). The temporal stability of the response in the chromophore-polymer conjugate was improved via simultaneous corona poling and thermal crosslinking. For example, the tetraphenylglycidylether of p-xylene (TPGX) employed as a multifunctional crosslinking moiety improved the temporal/thermal/oxidative stability to 90% retention of the original NLO response on aging in air at 100$spcirc$C for more than 1500 hours. Differential scanning calorimetry and infrared spectroscopic investigations guided curing protocols to enhance observable glass transition temperatures ($Tsb{g})$ of the crosslinked chromophore-polymer system from 125$spcirc$C to 255$spcirc$C.