Polyisoimide for In-Situ Rigid-Rod Molecular Composite Applications

摘要

A new material concept using in-situ rod formation from a coil like poly(tetramethyl isoimide) was explored for rigid rod molecular composite applications. Its feasibility relies mainly on an adequate degree of isomerization leading to a rod like polyimide of sufficient length for reinforcing the composite. Isomerization induced thermally was demonstrated in solutions and in the solid state with visible-light and infrared spectroscopies. X ray scattering revealed that the polyisoimide was amorphouse while the polyimide was highly crystalline. However, gel permeation chromatography showed a low degree of isomerization and possible polymer degradation. This was further supported by the absence of birefringence and anisotropy in light scattering from the converted polyimide. Computations on related dimers indicated that a high degree of isomerization was unlikely due to polyisoimide conformational restriction. Attempts to fabricate molecular composites utilizing this concept did not result in rigid-rod reinforcement from the polyimide. Keywords: Thermal isomerization; Polyisoimide; Polyimide; Molecular composite; Infrared spectroscopy; Gel permeation chromatography; X ray scattering; Molecular modeling. (MJM)