polymers the keys that enable nanostructured chemicals to function as molecular level porogens are 1 their unique size with respect to polymer chain dimensions and 2 their ability to be compatibilized and overcome repulsive forces that induce incompatibility and expulsion of the nanoreinforcing agents by the polymer chains it has long been known that in the solid state all polymers including amorphous semi crystalline crystalline rubbers etc possess considerable amounts of internal and external free volume fig3 the amount of free volume present is highly dependent upon the polymer composition morphology and the thermodynamic and kinetic factors associated with its nonequilibrium and equilibrium properties the free volume of a polymer has a tremendous impact on its physical properties since it is within this volume that the properties such as thermal conductivity gas liquid diffusion and permeability are controlled polymer morphology is another factor that contributes greatly to the accessibility of free volume in a polymer system for example denser regions or phase separation within a polymer can both increase and decrease the thermodynamic and kinetic access to such regions fig4 the size of poss is roughly equivalent to that of most polymer dimensions thus at a molecular level poss can effectively introduce porosity into existing polymer morphologies see table 1 poss 39 s ability to occupy specific sites within the amorphous and crystalline region of polymers enables alteration of the size of the porosity contained within the polymer the availability of a wide range of sizes of poss nanostructures cages further augments this capability fig5 6 furthermore because poss nanostructured chemicals possess.