Colorless and transparent polyimide nanocomposites: Thermo-optical properties, morphology, and gas permeation

A series of colorless and transparent polyimide (PI) hybrid films was synthesized from bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BTDA) and bis[4-(3-aminophenoxy)phenyl] sulfone (m-BAPS) with various clay contents, by solution intercalation polymerization to poly(amic acid)s, followed by thermal imidization. The thermal properties, morphologies, optical transparencies, and gas permeations of the PI hybrid films were examined for organoclay loadings ranging from 0 to 40 wt%. Up to a clay loading of 20 wt%, the clay particles were found to be highly dispersed in the PI matrix without any agglomeration of particles. However, for a clay content above 20 wt% some agglomerated structures form in the polymer matrix. The thermal and oxygen barrier properties of the PI hybrid films were gradually improved by increasing the organoclay content from 0 to 40 wt%. However, the optical transparency of the PI hybrid films deteriorated with increasing organoclay content.