Abstract

The thermal stability of the dipole orientation is a critical issue for poled polymers. Particularly for the newly developed photo-induced-poling (PIP) technique [1], it was shown that the dipole orientation is less stable than for thermally assisted poling (TAP) [2]. Physical methods to improve the thermal stability are thus highly de­sirable. Physical aging under applied field is known to significantly enhance the long-term stability of the dipole orientation [3]. Here, we study the improvement in the thermal stability of the dipole orientation achieved with physical aging under field after photo-induced and thermally assisted poling, using the recently introduced pyroelectric techniques (pyroelectric relaxation spectroscopy (PRS) and pyroelectric thermal analysis (PTA) [4]). In particular it is shown that two routes are possible to improve the thermal stability following PIP. One route is the use of high glass- transition polymers and PIP at a higher temperature, the other is physical aging under field after removing the pump light. The experimental results are discussed within the framework of a modified Narayanaswamy-Moynihan model. All the ex­periments were performed on P(S-MA)-DR1 side-chain polymers from Sandoz [5] (T_G of 140°C or 165°C).

© 1995 Optical Society of America