Differently-catalyzed silica-based precursors as functional additives for the epoxy-based hybrid materials

Two types of liquid pre-condensed silica-based precursors bearing epoxy groups were synthesized using the solvent-free sol-gel process of (3-glycidyloxypropyl)trimethoxysilane (GPTMS), in the presence of either basic (DABCO) or neutral (DBTL) catalyst, and further applied for modification of epoxy (DGEBA) – amine (Jeffamine™ D-230) glassy network. The prepared epoxy-silica hybrid materials were characterized by a set of methods including UV–vis, SAXS, TEM, AFM, DMTA, tensile tests, TGA and XRF. All hybrids were optically transparent regardless to the silica-based precursor type and its content showing an improvement mainly in dynamic shear storage modulus in rubbery region (up to 4.3 times), energy to break (up to ∼ 62%), elongation at break (up to ∼ 50%) and thermooxidative stability. The developed procedure is particularly suitable for preparation of fully-transparent massive bulk materials in which the presence of water and volatiles from the sol-gel is highly undesirable. [Display omitted] •Glassy epoxy-amine matrix was modified by the highly-condensed silica-based precursors prepared by the solvent-free sol-gel.•Obtained hybrids revealed different morphologies dependent on the type of sol-gel catalyst.•Improvement in mechanical properties and thermooxidative resistance was achieved for low precursor loadings - 1.8 wt%.•All prepared hybrid materials exhibited high optical transparency.