Water sorption and activation energy in polyimide thin films

Abstract

The water sorption behavior and the activation energy were investigated for various chemical structure polyimide thin films; BPDA‐PDA, BPDA‐ODA, PMDA‐ODA, and 6FDA‐ODA. The activation energy for the water diffusion varied in the range of 5.53 to 9.27kcal/mol, and was in the increasing order: BPDA‐PDA < BPDA‐ODA < PMDA‐ODA < 6FDA‐ODA. BPDA‐PDA and BPDA‐ODA polyimide films showed relatively well‐ordered morphological structure, which results in relatively low diffusion coefficient and high activation energy. It was found that the diffusion coefficient and the activation energy are significantly related to the in‐plane orientation, crystallinity, and packing order in the polyimide thin films. The morphological structure was predominant factors for the water diffusion coefficient and activation energy in the polyimide thin films. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2714–2720, 2000

Water sorption behaviors of the BPDA-based polyimide films depending upon the structural isomers of diamine

“…These were described in our previous literature. [11][12][13][14][15][16][17][18][19] All the sorption isotherms were analyzed with Fick's second law given by Crank and Park 20,21 :…”

“…This suggests that there may be no apparent morphological difference in the isomeric BPDA-DDS polyimide thin films. [15][16][17][18][19] From the water sorption results, it was found that the polyimide thin films with para-oriented linkage (p, p,pЈ, or p,pЈ) showed relatively lower diffusion coefficient and water uptake than the corresponding polyimide thin films with meta-oriented linkage (p, p,mЈ, or m,mЈ). In addition, both water uptake and diffusion coefficient are quite different from each other depending on the sort of polyimide.…”

“…Accordingly, it is simply expected that the water sorption behaviors of the polyimide thin films may be solely dependent on the morphological and chemical structures. [15][16][17][18][19] Water sorption behaviors may be due to the differences in the chemical affinity to water molecules and the concentration of polar groups such as carbonyl group (ϾCAO), carboxyl group (OCOOH), and sulfonyl group (ϾSO 2 ). 29,30 It is well known that the solubility of a given polymer in various solvents is largely determined by its chemical structure, and structural similarity favors solubility itself.…”

“…It suggests that the water sorption of the polyimide thin films may be significantly affected by the morphological structure: crystallinity, chain order, and packing order. [15][16][17][18][19] Morphological Structure…”

“…To investigate this, the polyimide thin films prepared from BPDA as a dianhydride and two type diamines (para-oriented and meta-oriented): p and m-phenylene diamine (PDA), p,pЈ and p,mЈ-oxydianiline (ODA), and p,pЈ and m,mЈ-diaminodiphenyl sulfone (DDS), were gravimetrically investigated by using a thin film diffusion analyzer. [11][12][13][14][15][16][17][18][19] The water sorption results were analyzed using a Fickian diffusion model in thin films and interpreted in terms of the chemical and morphological structures.…”