An insight into molecular relaxation of organic-inorganic hybrids based on epoxy resin

Epoxy organic-inorganic hybrids were prepared with epoxy-functionalized polyhedral oligomeric silsesquioxane (POSS-E). Different POSS-E molecules were incorporated into the epoxy network, one containing a mainly fully condensed cubic cage structure, and the other formed by a mixture of fully and partially condensed structures, in which the silanol end groups were present. The dispersion and distribution of POSS-E molecules into the resultant epoxy system were evaluated by DMA. A significant change in the tan 8 curve at the glass transition region was observed, which broadened and shifted to lower temperatures with higher POSS-E content. Additionally, a higher storage modulus value at the rubbery region was observed for epoxy hybrids compared with epoxy resin. Both behaviors were associated with the POSS-E molecular structure and its interaction with the neighborhood into the epoxy network.