Epoxy−amine networks were modified with well-defined inorganic building blockspolyhedral oligomeric silsesquioxanes (POSS). POSS molecules were incorporated in the organic−inorganic networks as dangling units of a network chain or as network junctions. Mono- or polyepoxide POSS monomers were used to prepare the two types of networks. The structure of the POSS-containing networks, including the structure evolution during network formation, was determined by SAXS, WAXS, and TEM. The POSS pendant on a network chain shows a strong tendency toward aggregation and crystallization, depending on the POSS organic ligands. During network formation, ordering of the crystal domains takes place. The POSS−POSS interaction is the main factor controlling the network structure. Also, the polyepoxy POSSs monomers aggregate in the organic matrix; however, during network formation the system becomes more homogeneous and POSSs as network cross-links become better dispersed. Still, in the cured organic−inorganic networks the POSS junctions are slightly aggregated, and the extent of aggregation increases with decreasing POSS cross-link functionality.

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This work addresses the use of ionic liquids (ILs) as additives for formation of epoxy-silica nanocomposites, via the simultaneous sol-gel process and epoxy network build-up. The application of different methylimidazolium based ILs allows controlling the silica structure and modifying interphase interaction, thus producing hybrids with diverse morphologies and improved mechanical properties. Both the anionic and cationic components of the ILs affected the hybrid formation and the final properties. The application of 1-decyl-3-methylimidazolium tetrafluoroborate ionic liquid together with HCl as an acid catalyst promotes both hydrolysis and condensation in the sol-gel process as well as the self-assembly ordering of the IL. This system produces a very fine hybrid morphology with well dispersed silica nanodomains and a significantly increased rubbery modulus due to physical crosslinking by the ordered domains of decyl-substituents.

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Polymer nanocomposites of epoxies with a novel filler, amino-functional butyltin oxide cage (stannoxane), were prepared and characterized. The nanofiller displays a promising antioxidizing effect, besides mechanical matrix reinforcement. The reinforcement can be assigned to physical interactions among the polymer bonded nanofiller. Moreover, the stannoxane cage undergoes a rearrangement to larger poly amino-functional nano-objects at higher temperatures, which highly reduces its extractability: it is practically not extractable from the nanocomposites in most cases. This, together with the fact that only a few weight percent are needed to achieve an optimal effect, makes it attractive as an antioxidative stabilizer. Epoxy–stannoxane nanocomposite synthesis, stannoxane reactivity and dispersion (morphology via TEM and SAXS), as well as the nanofiller effect on mechanical properties (DMTA) and on thermal stability are discussed. A brief comparison is drawn between the stannoxanes and the previously investigated POSS nanofiller.

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