In-situ study of the nonlinear optical responses and dynamics for crosslinked and uncrosslinked polymers

We performed the in-situ experimental study of nonlinear optical responses and dynamics for crosslinked- and uncrosslinked-polymers by changing the poling and relaxation profiles. In the characterization both second harmonic generation and photoinduced birefringence were employed. Two newly synthesized polymer structures, P(MMA-Co-MMCN) (0.7:0.3) with chromophores (A) and P(MMA-Co-IPO) (0.5:0.5) without chromophore (B) were adopted as representative polymeric systems. When the dipoles in the two polymeric systems (A) and (B) were thermally crosslinked to the polymer main chain along the electric field, the rotational mobility of dipoles were found to be suppressed, resulting in the improvement of thermal stability. In order to understand the higher thermal stability of the crosslinked polymer system, we investigated the in-situ second harmonic generation response at various temperatures.