We have several efforts directed towards the preparation of foams from organosilicon polymers-polysilanes and polysilsesquioxanes. These materials would be attractive for thermal or dielectric insulation materials that are nonflammable and non-charring. Organic polymer foams (such as Styrofoam TM) are widely used as low density, insulating materials with pore on the order of microns or greater in size In comparison, pores in gels are hundreds of nanometers in diameter or less. Most are physical foams prepared from a glassy or semicrystalline organic polymer that it “blown” with a gas then dried in place. Alternatively, foams can be prepared by thermally induced phase separation of a similar organic polymer from a solvent followed by drying. Because most organosilicon polymers have low Tg’s and are amorphous, few reports of foams exist. We were able to prepare polysilane foams using thermally induced phase separation followed by freeze or supercritical drying. Polysilsesquioxane foams can not be prepared directly because of the materials’ low TG’s. We were able to chemically generate polysilsesquioxane foams through a base-catalyzed disproportionation reaction of polyhydridosiloxanes that also generated a chemical blowing agent.

Contact: Doug Loy