Silsesquioxane Barrier Materials

Cubic octameric silsesquioxanes, because of their octahedral structures and nanometer size, represent potentially very useful nanoconstruction sites. Here we report the reaction of octaaminophenylsilsesquioxane (OAPS) with a variety of epoxides and dianhydrides and their subsequent heat treatment to form nanocomposite films with exceptional oxygen barrier properties. While solution-cast films give relatively low oxygen transmission rates (OTR), casting followed by warm-pressing lowers the OTR to values competitive with commercially available high-performance barrier films. The lowest OTR measured was obtained with a warm-pressed bilayer films consisting of OAPS/tetraglycidyl- m -xylenediamine and OAPS/2,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate with OTRs < 1 cm 3 20 μm/(m 2 day atm). These silsesquioxane films are thermally very robust, particularly the OAPS/imide films (>500 °C when fully cured), making them ideal for electronics packaging and encapsulation applications.