Preparation and properties of montmorillonite/organo-soluble polyimide hybrid materials prepared by a one-step approach

Montmorillonite (MMT)/organo-soluble polyimide (PI) hybrids were prepared u sing a one-step approach. The organo-modified MMT was dispersed in a soluti on of diphenylether-3, 3'4,4'-tetracarboxylic dianhydride and 4,4'-diamino- 3,3'-dimethyldiphenylmethane. The solution polycondensation followed by a d irect solution imidization at 180 degreesC resulted in MMT/PI hybrid soluti ons. From wide angle X-ray diffraction (WAXD) and transmission electron mic roscopy (TEM) results, the MMT is basically exfoliated in the hybrid films cast from the solutions when the MMT content is below 5 wt%. Further increa se in the MMT content leads to severe aggregation. The properties of a MMT/ PI hybrid are significantly dependent upon the MMT content. When the MMT co ntent is below 6 wt%, the introduction of the MMT leads to strengthening an d toughening to the PI matrix at the same time. The introduction of the MMT also results in improved thermal stability, marked decrease in coefficient of thermal expansion, slight increase in glass transition temperature and increase in modulus. (C) 2001 Kluwer Academic Publishers.