Synthesis and characterization of copolyimides with high solubility

Abstract

AbstractA series of copolyimides were prepared from various diamines (polysiloxane and isophorone units) with aromatic tetracarboxylic dianhydrides via a two‐step (thermal imidization) method. The monomers and polymers were produced in high yields, and the copolyimides containing SiOC bonds and asymmetric meta catenation in the polymer backbone exhibited good solubility. The glass‐transition temperatures (Tg's) of all the copolyimides were found to be 201–262 and 215–258°C by differential scanning calorimetry (DSC) and dynamic mechanical analysis, respectively. Thermogravimetric analyses indicated that the polymers were fairly stable up to 502–578°C (10 wt % loss in N2) and 490–574°C (10 wt % loss in air). The char yields at 800°C in N2 and air atmospheres were 26–59 and 20–53%, respectively. The copolymerization results, determined with 1H‐NMR and DSC, indicated a random copolymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1963–1970, 2003