A high reactive penta-coordinated organic silicon compound(KSi(OCH 2CH 2O) 2(OCH 2CH 2OH)) was prepared, by the reaction of silica with ethylene glycol and potassium hydroxide, and di-hydroxy tetra coordinated silicon (OCH 2CH 2O)Si(OCH 2CH 2OH)(OCH 2CH 2OCH 2CH 2OH)(DHTS) was prepared by reacting penta-coordinated silicon complex with ClCH 2CH 2OH. Composite film of DHTS/polyvinyl butyral(PVB) was prepared by a sol-gel method. The thermal property, including glass-transition temperature of the composite film were examined. When the mass ratio of PVB to tetra coordinated silicon was 1∶1.7, the on set mass loss temperature of the composite film was increased by 27 ℃ in comparison with PVB. The transparency and tenacity of the composite film were all increased. But increase of the mass fraction of DHTS could decrease the decomposition temperature of the film.
