Polyimide Nanocomposites Prepared with a Novel Aromatic Surfactant

Abstract

Montmorillonite clays modified with 1,5-bis(3-aminophenoxy)-3-oxapentane dihydrochloride (BAOD) were used in the preparation of polyimide/organoclay hybrid films. Organoclays with varying surface charge based upon BAOD were prepared and examined for their dispersion behavior in the polymer matrix. Initial evaluation was performed by preparing high molecular weight poly(amide acid) solutions in the presence of the organoclays at a 3 wt% loading. Films were cast and subsequently heated to 300 °C to cause imidization. The resulting nanocomposite films were characterized by transmission electron microscopy and x-ray diffraction. It was found that the clay's cation exchange capacity (CEC) played a key role in determining the extent of dispersion in the polyimide matrix. Considerable dispersion was observed in nanocomposite films prepared from organoclays possessing medium and high CECs. One organoclay that dispersed well was further evaluated in nanocomposite films at weight loadings of 5 and 8%. The nanocomposite films were characterized by transmission electron microscopy, x-ray diffraction, and thin-film tensile testing. High levels of clay dispersion were achieved even at the higher clay loadings. Mechanical testing of these films showed that the moduli of the materials increased with increasing clay concentration, but the strength and elongation were generally adversely affected.