Catalytic polymer/copper composite thin films formed at the liquid/liquid interface through self-assembly and hydrolysis process

Two kinds of microstructures, microporous film of poly(2-vinylpyridine) (P2VP)/Cu2+ and thin film composed of P2VP and nano-shuttles and microbelts of Cu(OH)2 were fabricated at the planar liquid/liquid interface formed by chloroform solutions of P2VP and aqueous solutions of cupric sulfate (CuSO4) and cupric acetate (Cu(CH3COO)2), respectively. The formation of the microporous film of P2VP/Cu2+ was associated with the adsorption and combination of P2VP molecules with Cu2+ ions, and self-assembly of the composite species at the liquid/liquid interface, while the formation of the composite P2VP/Cu(OH)2 structure was attributed to the adsorption of the polymer molecules and the hydrolysis of Cu2+ ions at the liquid/liquid interface when Cu(CH3COO)2 aqueous solution was used. The incorporated Cu2+ ions and Cu(OH)2 nanoparticles transformed to Cu nanoparticles after reduction by KBH4. These composite nanostructures exhibit different catalytic behaviors for the reduction of 4-nitrophenol (4-NP). The catalytic activity of the microporous structure of polymer doped with Cu nanoparticles increased and then decreased gradually for different cycles, which was due to the gradually outward diffusion and part leaching and/or aggregation of the incorporated Cu nanoparticles because the interaction of Cu nanoparticles with the polymer is weak. While the nano-shuttle and microbelt structures composed of Cu nanoparticles exhibited higher and durable catalytic activity.