Effect of isomeric oxydiphenylene diamine on the water sorption behavior of high temperature polyimide thin films

The effects of isomeric oxydiphenylene diamines (ODA), 3,4'ODA and 4,4'ODA, on the water sorption behavior in pyromellitic dianhydride (PMDA)-ODA, bip henyltetracarboxylic dianhydride (BPDA)-ODA, 3,3',4,4'-benzo phenonetetraca rboxylic dianhydride (BTDA)-ODA. and 4,4'-hexafluoroisoyropylidenediphthali c anhydride (6FDA)-ODA polyimides were gravimetrically investigated. Water sorption curves were reasonably well fitted by Fickian diffusion despite th eir morphological heterogeneities in the polyimide thin films. However, the effects of isomeric ODA on the water sorption were quite different dependi ng upon the sort of polyimide. The mutual diffusion coefficient of water an d 4,4'ODA based polyimide films varies in the range of 3.0 x 10(-10) cm(2) s(-1) to 15.2 x 10(-10) cm(2) s(-1), and is in the increasing order: BPD,4- 4.4'ODA < BTDA-4,4'ODA-PMDA-4.4'ODA < 6FDA-4,4'ODA. The water uptake varies from 1.62wt% to 3.25 wt%. and is in the increasing order: BPDA-4,4'ODA < 6 FDA-4,4'ODA < PMDA-4.4'ODA < BTDA-4.4'ODA. However, the diffusion coefficie nt for 3,4'ODA based polyimide films varies in the range of 6.7 x 10(-10) c m(2) s(-1) to 8.6 x 10(-10) cm(2) s(-1). and is in the increasing order: BP DA-3.4'ODA < 6FDA-3.4'ODA-BTDA-3.4'ODA-PMDA-3,4'ODA. Thr water uptake varie s from 2.02 wt% to 2.98 wt%, and is in the increasing order. 6FDA-3,4'ODA < BPDA-3,4'ODA < BTDA-3,4'ODA < PMDA-3,4'ODA. Polyimides having higher chain order, highly crystalline structure, and smaller mean intermolecular dista nce revealed relatively lower diffusion coefficients and water uptakes in e quilibrium.