Atomistic Modeling of Composite Electrooptic Materials Based on Linear Polyimides with Guest Azochromophores

Atomistic modeling of materials based on linear polyimide oligomers (PIs) and composites with PIs as polymer matrix and azochromophores-guests containing tricyano moiety as an acceptor fragment is performed; chromophore content is 10, 20 and 30 wt %. Glass transition temperature, Tg, of the named materials is calculated to be ~600 K. Reduced Tg is obtained for composites compared to that of a PI material; Tg values are decreasing notably with the growth of chromophore content. To study the ability of chromophores to orient in the PI matrix, the modeling in the applied electric field was performed for the first time showing that poling field strength should be rather high: at 500 V/μm acentric order parameter 0.35 is obtained. High free volume was estimated for the composite material with of chromophore content 10 wt %; a great number of noncovalent interactions in the composite give grounds to predict high relaxation stability of electrooptic response for these materials.