Effect of in situ-formed polydimethylsiloxane on the properties of polyimide hybrids

Polyimide-polydimethylsiloxane (PI-PDMS) hybrids were synthesized by combining an in situ sol-gel reaction of diethoxydimethylsilane (DEDMS) and imidization of poly(amide acid) (PAA) prepared from pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (ODA). Transparent hybrid films were obtained with up to 3 wt.% PDMS content corresponding to the relatively small domain size of PDMS as confirmed by scanning electron microscopy. The hybrid films with up to 3 wt.% of PDMS content showed higher tensile modulus, strength and elongation at break than those of pristine PI, due to the in situ-formed PDMS. The thermal stability of the hybrids also increased with the increase of PDMS content, as evidenced by TGA.