New Aminophenylsilsesquioxanes, Synthesis, Properties and Epoxy Nanocomposites

Richard Laine

K. Takahashi, S. Sulaiman, J.M. Katzenstein, S. Snoblen, and R.M. Laine (2006)

Australian J. Chem., 59:564-70.

New aminophenylsilsesquioxanes, dodecaaminophenylsilsesquioxane (NH2PhSiO1.5)12 (DAPS), and hexadecaaminooctaphenylsilsesquioxane ((NH2)2PhSiO1.5)8 (HDAPS), were prepared from dodecaphenylsilsesquioxane (PhSiO1.5)12 (DPS), and octaphenylsilsesquioxane (PhSiO1.5)8 (OPS), by nitration in fuming HNO3, followed by reduction with HCO2H/Et3N/Pd/C. The effects of the cage structure and numbers of NH2 groups on the chemical and physical properties of these compounds were compared with octaaminophenylsilsesquioxane (NH2PhSiO1.5)8 (OAPS), and analogous epoxy resin nanocomposites. The cage structure does not affect nitration patterns (primarily meta and para), but affects coefficients of thermal expansion (CTEs), likely because of overall crosslink densities and because of the epoxy tether structures joining cube vertices. CTEs as low as 25 ± 2 ppm°C–1 were found, perhaps the lowest reported for an unfilled epoxy resin. The thermal stabilities of synthesized HDAPS epoxy nanocomposites were 20–30°C lower than those made with OAPS. This result may be a consequence of less-complete curing due to gelation before stoichiometric curing, caused by the much higher crosslink densities in OAPS.

Nanocomposites, silsesquioxanes, Epoxy Resins