Abstract: | Copolyimides containing BTDA-3DDS and BTDA-4ODA units have been synthesized by solution imidization methods. The copolyimides have high Tg's (267–283°C) and high decomposition temperatures (540–575°C; nitrogen); both properties are dependent on composition. Those copolymides with low concentrations of BTDA-4ODA are generally soluble in organic solvents, whereas those copolyimides with higher BTDA-4ODA content are only partially soluble or insoluble. However, all the copolyimides prepared can be compression molded. It has also been found that segmental motion above Tg is heavily suppressed in the BTDA-4ODA homopolymer relative to that in the BTDA-3DDS homopolymer. This reduction in molecular motion may severely hinder the solubility and fusibility of the BTDA-4ODA homopolymer. © 1993 John Wiley & Sons, Inc. |