An Approach to Epoxy Resins: Oxysilylation of Epoxides

We report here a method of synthesizing self-reinforced epoxy resin nanocomposites via oxysilylation that avoids the use of polyamines. Nanocomposites with three-dimensional (3-D) ordered architectures can be produced by reaction of [HSiMe2OSiO1.5]8 (OHS) linked via diepoxides using the Piers–Rubinsztajn reaction or oxysilylation. We describe several basic aspects of oxysilylation of diepoxides with TMDS (HMe2SiOSiMe2H, tetramethyldisiloxane), OHS, D4H [(CH3SiHO)4, tetramethylcyclotetrasiloxane], and D5H [(CH3SiHO)5, pentamethylcyclopentasiloxane] in mixtures of dichloromethane and hexane, or as simple mixtures catalyzed by B(C6F5)3 at ambient temperature. Diepoxides react with TMDS to form mostly linear polymers with MWs of 1–20 kDa per gel permeation chromatography (GPC). These polymers are stable in boiling water for several hours. Diepoxides with simple structures react rapidly. As the complexity of the diepoxide increases, reaction rates decrease, which is often coincident with gelation with higher MWs. Oxysilylation of diepoxides with OHS typically forms gels before full completion of the reaction due to high cross-link densities. These gels retain Si–H bonds, yet are also stable in boiling water (5 h) and capable of solvent uptake.