Montmorillonite/polyimide (3,3‘,4,4‘-benzophenone tetracarboxylic dianhydride-4,4‘-oxydianiline, BTDA-ODA) nanocomposites displaying different morphological, thermal, and mechanical characteristics were synthesized by involving mono-, di-, and trifunctional group swelling-agent-modified montmorillonite and poly(amic acid). It was found that the dispersion of silicate layers in BTDA-ODA shifted from intercalated to exfoliated structures when the number of functional groups of the swelling agent increased to three as evidenced from X-ray diffraction and transmission electron microscopy studies. The improved morphology of the nanocomposites resulted in their enhanced mechanical and thermal properties. In particular, a 70% increase in Young's modulus, a 50% increase in the maximum stress, and a 30% reduction in the coefficients of thermal expansion for the case of BTDA-ODA nanocomposites containing 5 wt % trifunctional group swelling-agent-modified montmorillonite as compared to that of pure BTDA-ODA.

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A process was developed for fine fabrication of amorphous IGZO TFTs and integrated circuits on flexible and colorless polyimide substrates. TFTs with field‐effect mobilities of ∼10 cm2/Vs and ring oscillators with propagation delay of 0.35 μs per stage were achieved on the polyimide substrates.

ABSTRACT:The thermal properties and the moisture absorption of three types of polyimide/montmorillonite nanocomposite were investigated: 3,3Ј,4,4Ј-biphenyltetracarboxylic dianhydride-4,4Ј-oxydianiline (BPDA-ODA); pyromellitic dianhydride-ODA (PMDA-ODA); and 3,3Ј,4,Ј-benzophenone tetracarboxylic dianhydride-ODA (BTDA-ODA). The inhibition effect on in-plane coefficients of thermal expansion (CTE) and moisture absorption of these polyimide nanocomposites by layered silicates from montmorillonite was found to decrease with the crystallinity in the pristine polyimides. The largest reduction, 30% in in-plane CTE occurred in the case of amorphous BTDA-ODA containing 5 wt % montmorillonite as compared with that of pure BTDA-ODA, while the reduction in in-plane CTE was 20% for the case of semicrystalline BPDA-ODA. The maximum reduction in moisture absorption, 43%, also took place for the case of 3/97 ODA-Mont/BTDA-ODA as compared with that of pure BTDA-ODA, whereas the semicrystalline 1/99 PPD-Mont/BPDA-ODA showed a 30% reduction as compared with that of pure BPDA-ODA.

The thermal properties and the moisture absorption of three types of polyimide/montmorillonite nanocomposite were investigated: 3,3′,4,4′‐biphenyltetracarboxylic dianhydride‐4,4′‐oxydianiline (BPDA‐ODA); pyromellitic dianhydride‐ODA (PMDA‐ODA); and 3,3′,4,′‐benzophenone tetracarboxylic dianhydride‐ODA (BTDA‐ODA). The inhibition effect on in‐plane coefficients of thermal expansion (CTE) and moisture absorption of these polyimide nanocomposites by layered silicates from montmorillonite was found to decrease with the crystallinity in the pristine polyimides. The largest reduction, 30% in in‐plane CTE occurred in the case of amorphous BTDA‐ODA containing 5 wt % montmorillonite as compared with that of pure BTDA‐ODA, while the reduction in in‐plane CTE was 20% for the case of semicrystalline BPDA‐ODA. The maximum reduction in moisture absorption, 43%, also took place for the case of 3/97 ODA‐Mont/BTDA‐ODA as compared with that of pure BTDA‐ODA, whereas the semicrystalline 1/99 PPD‐Mont/BPDA‐ODA showed a 30% reduction as compared with that of pure BPDA‐ODA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1742–1747, 2001