Photo-Alignment Characteristics of Charge-Transfer Complexes Forming Polyimides with Tetramethyl Phenylene Diamine

摘要

The photo-alignment characteristics of 2,3,5,6-tetramethyl-1,4-phenylene diamine (TeMPD)- based polyimides with a good electron-releasing property were systematically investigated, such as 3,3,4,4-diphenylsulfonetetracarboxylic dianhydride-TeMPD, 4,4-(hexafluoroisopropylidene) diphthalic anhydride-TeMPD, and cyclobutane-1,2,3,4-tetracarboxylic dianhydride-TeMPD. TeMPD-based polyimides with various charge-transfer energy levels, varying from the lowest occupied molecular orbital in the diamine component of the polyimide to the highest occupied molecular orbital in the acid component, were used. All of the TeMPD-based polyimide films irradiated with linearly polarized ultraviolet light exhibited photo-alignment characteristic with the same direction, regardless of the different imidization ratios. The chemical structure and electronic state depended on the formation of charge-transfer complexes and did not affect the apparent photo alignment.