Water-sorption behavior ofP-phenylene diamine-based polyimide thin films

Abstract

Four different p‐PDA–based polyimide thin films were prepared from their respective poly(amic acid)s through thermal imidization at 400°C: poly(p‐phenylene pyromellitimide) (PMDA‐PDA); poly(p‐phenylene biphenyltetra carboximide) (BPDA‐PDA); poly(p‐phenylene 3,3′,4,4′‐oxydiphthalimide) (ODPA‐PDA); and poly(p‐phenylene 4,4′‐hexafluoroisopropylidene diphthalimide) (6FDA‐PDA). Water‐sorption behaviors of polyimide films were gravimetrically investigated at 25°C and 22–100% relative humidity by using the modified electromicrobalance (Thin Film Diffusion Analyzer). The diffusion coefficients of water for the polyimides varies in the range of 1.6 to 10.5 × 10−10 cm2/s, and are in the increasing order: BPDA‐PDA < PMDA‐PDA ∼ ODPA‐PDA < 6FDA‐PDA. The water uptakes of polyimides vary from 1.46 to 5.80 wt %, and are in the increasing order: BPDA‐PDA < ODPA‐PDA < 6FDA‐PDA < PMDA‐PDA. The water‐sorption behaviors for the p‐PDA–based polyimides are closely related to the morphological structure; specifically, the diffusion coefficients in p‐PDA–based polyimide thin films are closely related to the in‐plane orientation and mean intermolecular distance, whereas the water uptakes are affected by the packing order. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1315–1323, 2000

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

“…Coated wafers were prebaked at 80°C for 30min on a hot plate. The prebaked samples were then placed in a curing oven and cured by the following cure schedule [11][12][13][14][15][16][17][18][19] : 150°C/30 min, 230°C/30 min, 300°C/30 min, and 400°C/60 min. 8 -11 The ramping rate for each step was 2.5°C/min and the cooling rate was 2.0°C/min for the curing process.…”

“…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 :…”

“…All of the water sorption isotherms were reasonably well fitted by a Fickian diffusion model [i.e., eq. (1)], regardless of morphological heterogeneities [11][12][13][14][15][16][17][18][19][22][23][24] due to the ordered and disordered phases. It indicates that the water sorption behaviors of the polyimide thin film Table I.…”

“…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.…”

“…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.…”