Aligning polymer main chain by pendent chromophore alignment: Optical and electrical methods

We have studied whether the main chain can be aligned by alignment of attac hed chromophores using two types of polymethacrylates carrying side-on atta ched and end-on attached chromophores. To align chromophores, nonpolar alig nment by optical pumping and polar alignment by the corona poling method we re used. To verify the alignment of the polymer main chain, we measured inf rared wave absorption for the characteristic vibration mode. The photoalign ment of side-on attached chromophore gave better aligning of the main chain s. The degree of photoalignment of main chains depended on the main chain c onformation as well as on the temperature at which samples were aligned. Th e degrees of alignment for main chains and that for the chromophores show m aximum values at a temperature a little lower than the glass transition tem perature. We could understand these behaviors with the free volume concept. Also, the degree of alignment for the side-on type was 2 times larger than that for the end-on type. This shows that, in the solid solution, cooperat ive interaction between polymer main chains and chromophores increases the rigidity and alignment of the polymer main chain. For the end-on attached c hromophore, the alignments of chromophores and polymer main chains by coron a poling were similar to those by optical pumping. But for the side-on atta ched chromophore, optical pumping was more efficient compared to the corona poling.