Dependence of water sorption in polyimides on the internal linkage in the diamine component

The dependence of the water sorption behavior of polyimide thin films upon different diamine fragments was gravimetrically investigated. It was found that the diffusion coefficient and water uptake were strongly dependent upon the internal linkage in the diamine fragment, and varied in the range of 1.6×10 −10 13.5×10 −10 cm 2/s and 1.52 ∼ 5.63 wt.%, respectively. The water sorption behavior of the polyimide films decreased with increasing bulkiness of the internal linkages in the diamine fragments: BPDA-PDA