HIGHLY POROUS POLYHEDRAL SILSESQUIOXANE POLYMERS - SYNTHESIS AND CHARACTERIZATION

Polyhedral octahydridosilsesquioxanes, [HSO1.5](8) (1) and [(HSiMe2O)S iO1.5](8) (3) were hydrosilylatively copolymerized with stoichiometric amounts of the octavinylsilsesquioxanes, [vinylSiO(1.5)](8) (2) and [ (vinylSiMe(2)O)SiO1.5](8) (4) in toluene using platinum divinyltetrame thyldisiloxane, ''Pt(dvs)'', as catalyst. The degree of condensation o f the resultant four copolymers ranges from 43% to 81% depending on in tercube chain lengths, as determined by solid state C-13 and Si-29 MAS NMR analyses, using cross-polarization (CP) techniques. The presence of residual functional groups was confirmed by diffuse reflectance inf rared Fourier transform spectroscopy (DRIFTS). Polymer porosities were measured using nitrogen sorption, positron annihilation lifetime spec troscopy (PALS), and small angle X-ray scattering (SAXS) methods. The combination of these three techniques allows a relatively complete des cription of the pore sizes and pore size distributions in these materi als. The pores in the cube interiors are similar to 0.3 nm in diameter , while those between the cubes range from 1 to 50 nm in diameter (for polymer 3 + 4). Nitrogen sorption analyses give specific surface area s (SSAs) of 380 to 530 m(2)/g with ''observable'' pore volumes of 0.19 -0.25 mL/g.