Silicon-containing polyesterimides

New silicon-containing polyesterimides have been synthesized by a solution polycondensation reaction, in a high-boiling-point solvent, of a silicon-containing diacid chloride (namely bis(p-chlorocarbonyl-phenylene)-diphenylsilane) with certain dihydroxy-compounds having preformed imide rings. All these polymers were soluble in polar amidic solvents, such as N-methylpyrrolidinone and dimethylformamide, and gave thin transparent films on casting their solutions. The polymers exhibited high thermal stability, with the initial decomposition temperature being above 400 degrees C for fully aromatic structures. Most of these polymers did show a glass transition: those containing only aromatic rings being in the range of 180-236 degrees C, while those having some ethylene units along with aromatic ones being in the range of 160-178 degrees C. The dielectric constants of the free-standing polymer films are in the range of 3.04-3.19. Very thin coatings, in the range of tens of nanometres, which were deposited onto silicon wafers, exhibited smooth and pinhole-free surfaces in atomic force microscopy investigations. All these characteristics are discussed and compared with those of related polyester-imides which do not contain silicon.