The Relationship between the Conformation of Polyimide Films and the Magnitude of the Pretilt Angle

Abstract

Seven alkylene aromatic polyimides have been synthesised. FT-IR spectra for the polyimides show small regular changes. This shows that the bulk structure of these polyimides changes in a regular fashion, while SEM pictures do not reveal any difference in the surface topology.

The dispersive and polar parts of the surface tension have been calculated. Although the total surface tension shows only small variations, there is a large odd-even effect in the dispersive and polar parts of the surface tension. This shows that there is a regular change in the structure close to the surface for this series of polyimides.

We also found a clear odd-even effect in the pretilt angles with ZLI-1132, and other nematic liquid crystals. We find that there is a decrease in the angle between the surface and the first molecule with increasing alkylene chain length, while the in-plane order shows a weak odd-even effect.

Key Words:

• Polyimide
• conformation
• pretilt
• in-plane-order