Siloxane- and imide-modified epoxy resin cured with siloxane-containing dianhydride

Abstract

Hydrosilylation of nadic anhydride by tetramethyldisiloxane yielded 5,5'-(1, 1,3,3-tetramethyl- 1, 1,3,3-disiloxanediayl)-bisnorborane-2,3-dicarboxylic anhydride (I), which further reacted with 4-aminophenol to form N,N'-bis(4-hydroxyphenyl)5,5'-(1,1,3,3-tetramethyl-1,1,3,3-disiloxanediallyl)-binorborane-2,3-dicarboximide(II) reacted with epichlorohydrin to form siloxane- and imide-modified epoxy (i.e. N,N'-diglycidylether-bis-(4-phenyl)-5,5'-(1,1,3,3-tetramethyl-1,1,3,3disloxanediallyl)-bis-norborane-2,3-dicarboximide (III) (Scheme 1). Various equivalent ratios of III/I for 1/1, 1/0.8 and Bisphenol F epoxy (830LVP DIC Co.)/I for 1/1, 1/0.8 were prepared and cured to produce four crosslinked materials. Thermal and dynamic mechanical properties were measured with TMA and DMA. Kinetic analysis was studied with dynamic DSC, which revealed a relatively lower curing activation energy of III/I systems, because the tertiary amine on the imide group catalyzed the curing reaction. III/I system also indicated moderate Tg, storage modulus but higher loss modulus as compared with Bisphenol F epoxy/I systems. These phenomena were interpreted by the fact that the siloxane group in III toughened the crosslinked materials. In addition, photos of SEM, carbon-mapping-SEM, oxygen-mapping SEM and siloxane-mapping-SEM indicated all homogeneity of these materials.