Preparation and properties of epoxy resin/silicone hybrids for electronic applications

Epoxy resin/silicone hybrids were synthesized through the cationic polymerization of a cycloaliphatic epoxy resin and a hydroxy-terminated poly(dimethyl siloxane) (PDMS) in different molar ratios. Molar ratios of the epoxy resin and silicone for the hybrids were 1/1, 1/0.75, 1/0.5, 1/0.25.3-Glycidoxypropyl-trimethoxysilane (GPTMS) was also added to the epoxy resin/silicone mixtures to improve the transparency by the reaction between GPTMS and the resin mixtures. The hybrids of epoxy resin/silicone became transparent with increasing the content of PDMS. The addition of GPTMS resulted in the large increase of transparency of the hybrids even at lower concentration of PDMS. Some opaque hybrid samples showed two glass transition temperatures in the thermograms obtained with differential scanning calorimetery (DSC). In case of the hybrids containing GPTMS, nanoparticles of silica were observed in transmission electron microscopy (TEM) images even though they appeared highly transparent after cure.