Effects of humidity, imidization history, and thickness on water sorption behavior of poly(p‐phenylene biphenyltetracarboximide) films

Abstract

SYNOPSISPoly(p-phenylene biphenyltetracarboximide) films with various thicknesses were prepared from the poly(amic acid) precursor by thermal imidization at 230-400°C for 1-10 h under a nitrogen atmosphere. The water sorption in the films was measured at 25°C over 22-100% relative humidity using a Cahn microbalance as a function of film thickness and thermal imidization history. The water diffusion in all the films followed nearly Fickian process despite the morphological heterogeneity due to the ordered and less ordered phases.The diffusion coefficient and water uptake varied in 0.85 X lo-'' -7.50 X lo-'' cmz/s and 0.12-2.4 wt %, respectively, depending upon humidity, film thickness, and imidization history. Both diffusion coefficient and water uptake increased with increasing humidity, but decreased as imidization temperature and time increased. With increasing film thickness, the diffusion coefficient increased whereas the water uptake decreased. The water sorption behavior was interpreted with the consideration of morphological variations, such as polymer chain order, in-plane orientation, and intermolecular packing order due to the film thickness and imidization history. 0 1995 John Wiley & Sons, Inc.

Water‐sorption behaviors of poly(3,4′‐oxydiphenylene pyromellitimide) films depending on the thickness variation

“…[17][18][19][20][21][22][23][24][25] Measurements were carried out in various humidities of 22-100% and various temperatures of 5-60°C. Morphological structures in the films were measured using WAXD (Rigaku Co., Model RINT 2500H) and a prism coupler (Metricon Inc., Model 2010).…”

“…The water-sorption behaviors were gravimetrically measured using a Thin Film Diffusion Analyzer [17][18][19][20][21][22][23][24] and interpreted together with humidity, film thickness, and morphological structure. The morphological structures in the films were characterized by wide-angle X-ray diffraction (WAXD) and prism-coupling analyses.…”

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 :…”

“…Here, the transmission pattern gives a structural information for the film plane, whereas the reflection pattern does a structural information for the out-of-film plane. [11][12][13][14][15][16][17][18][19]32 BPDA-pPDA exhibited multiple diffraction peaks in both the transmission and reflection patterns. However, the characteristic diffraction peaks in the transmission pattern, which correspond to the intermolecular ordering, are very prominent.…”

“…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.…”