Modulating\nthe Contact Angle between Nonpolar Polymers\nand SiO<sub>2</sub> Nanoparticles

Polymer–nanoparticle interactions play an important\nrole\nin determining the morphology and properties of polymer nanocomposites\nand controlling the polymeric reactions involving heterogeneous catalysts.\nHere, we modulate the interactions between nonpolar polymers and nanoparticles\nby modifying the nanoparticle surface chemistry and quantify the interaction\nstrength through direct contact angle measurements. We investigate\nthe interactions of three nonpolar polymers, polystyrene, polyethylene,\nand polycyclooctene, with silica nanoparticles whose surface chemistry\nhas been modified by atomic layer deposition of titania and calcium\ncarbonate and by alkyl silanization. Significant differences in polymer–nanoparticle\ninteractions are observed, which can be attributed to differences\nin the polarizability of the polymers and oxide surface composition.\nCompared to fully hydrogenated polycyclooctene, polycyclooctene is\nshown to have stronger interactions with most metal oxides; however,\nthis trend is reversed following alkyl silanization of the silica\nnanoparticles, which makes the surface of the particles less polar.\nThese differences in interactions can be leveraged to make polymer\nnanocomposites with unique properties and enable the selective conversion\nof polymers without the need for separations.