Synthesis and Tuning of Gold Nanoparticles Supported on Polymorphic Semicrystalline Nanoporous Polymer for Catalytic Aerobic Oxidation of Alcohols

The wide and complex tunability of gold nanoparticles (AuNPs) supported on nanoporous, semicrystalline, and polymorphic polymer matrices consisting of syndiotactic polystyrene (sPS) or multiblock syndiotactic polystyrene-co-cis-1,4 poly(butadiene) (sPSB) is herein described and correlated with the performances in aerobic oxidation of (+/-)-1-phenylethanol. Impregnation or deposition-impregnation synthetic methods yielded AuNPs of middle size (10-20 nm) on the surface of polymer grains. The co-precipitation method leads to small AuNPs (4-5 nm) homogenously dispersed in the support with quantitative entrapment of the gold. Thermal or solvent annealing afforded modifications of polymer crystalline phase and AuNPs morphology. The annealing with chloroform/water mixture increases the crystallinity of the nanoporous forms and converts compact gamma and beta phases into the nanoporous epsilon and delta phases. The thermal treatment of the AuNPs-sPS(B) catalysts afford defective NPs with enhanced catalytic activity. The solvent-induced formation of the nanoporous forms improves permeability to solvents and reactants and, in turn, the catalytic properties