Relaxation Processes in Nonlinear Optical Side-Chain Polyimide Polymers

Optical, nonlinear optical and electro-optic properties of modified side-chain polyimide polymers as shown in Fig. 1 have been determined. Relaxation processes in these nonlinear optical (NLO) polymers are of considerable interest for obtaining a better understanding of the long-term stability of potential devices fabricated from these materials. The relaxation mechanisms of the side-chain chromophores have been investigated above and below the glass transition by second-harmonic decay, dielectric relaxation and differential scanning calorimetry measurements. We find that the time-temperature relaxation behavior of the NLO chromophores in a variety of polymer systems can be understood in terms of current phenomenological descriptions of the glass transition with the aid of a scaling relation.