A polydisilahydrocarbon, namely, poly(tetramethyldisilylene-co-styrene), synthesized from dimethyldichlorosilane and styrene in 1:0.5 mol ratio under dechlorination conditions was evaluated as an atomic oxygen (AO) resistant coating for polyimide film and C-polyimide composite. Exposure of the polymer coating on a quartz plate to an AO fluence of 2.1 x 10(21) atoms/cm(2) resulted in practically no mass loss, indicating the AO resistance of the polymer. Ten percent solution of the polymer in toluene was applied on aluminized Kapton(R) polyimide film (125 mum thick) to obtain a coating thickness of similar to 5 mum on the unaluminized surface. In a similar way, the coating was applied on a C-polyimide composite. The coated and uncoated samples of Kapton(R) film and C-polyimide composite were exposed to AO in a plasma barrel system. The uncoated aluminized Kapton(R) film (125 gm) lost 6.35 T /cm(2) when exposed to AO fluence of 1.6 x 10(21) atoms/cm(2) whereas the corresponding coated film lost only 0.14 mg/cm(2) even after exposure to AO fluence of 2.1 x 10(21) atoms/cm(2). In the case of the C-polyimide composite, the uncoated sample lost 63.64 mg/cm(2) on exposure to AO fluence of 1.8 x 10(21) atoms/cm(2) whereas the coated one lost only 0.21 mg/cm(2) even after exposure to AO fluence of 2.1 X 10(21) atoms /cm(2). SEM studies suggest that the coating offers good protection to the substrates. Formation of cracks on some portions of the coating was noticed. (C) 2004 Wiley Periodicals, Inc.