10.1007/s11451-008-3027-3

Abstract

The time dependence of the nonlinear optical properties of the films prepared from silicon-containing poly( o -hydroxyamide) with a covalently bound 4-nitroazobenzene-based chromophore in a side chain is investigated in isothermal and thermally stimulated modes. It is revealed that, when the onium salt, i.e., triphenylsulfonium hexafluorophosphate, is added to a polymer solution, the second harmonic generation signal is characterized by an unusual time dependence. The assumption is made that the introduction of the onium salt favors the formation of the benzoxazole structure during the process of polarization (poling). This structure facilitates the orientation of nonlinear optical fragments and, hence, leads to an improvement of the nonlinear optical properties of the polymer film.