Preparation and properties of polyimide-silica hybrid films with conjugation of the polyimide and silica by a sol-gel process using 3-(triethoxysilyl)propyl succinic anhydride

New polyimide-silica hybrid materials were prepared using the polyamic acid synthesized by copolymerization of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 4,4′-oxydianiline (ODA) and an A2A′-type tri-functional amine, 1,1-bis(4-(aminophenoxy)phenyl)-1-(4-(4-amino-2-trifluoromethylphenoxy)phenyl)ethane (1) (BTDA:ODA:1 = 7:6:1 in the molar). 3-(Triethoxysilyl)propyl succinic anhydride(TESSA) was reacted with amino groups in polyamic acid to introduce ethoxysilyl moiety which act as conjugation site for silica. The polyimide-silica hybrid films were prepared by a sol-gel reaction of tetraethoxysilane (TEOS) in a solution of the polyamic acid, followed by thermal imidation. Self-standing films were obtained with up to 50 wt.% silica, and transparent films were obtained at up to 40 wt.% silica. Dynamic-mechanical and mechanical analyses were carried out to examine the properties of hybrid films.