Synthesis of Silver Nanoparticles Loaded onto Polymer-Inorganic Composite Materials and Their Regulated Catalytic Activity

We present a novel approach for the preparation of polymer-TiO(2) composite microgels. These microgels were prepared by the in situ hydrolysis and condensation of titanium tetrabutoxide (TBOT) in a mixed ethanol/acetonitrile solvent system, using poly(styrene-co-N-isopropylacrylamide)/poly(N-isopropylacrylamide-co-methacrylic acid) (P(St-NIPAM/P(NIPAM-co-MAA)) as the core component. Silver nanoparticles (AgNPs) were controllably loaded onto the polymer-TiO(2) composite microgels through the reduction of an ammoniacal silver solution in ethanol catalyzed by NaOH. The results showed that the P(St-NIPAM)/P(NIPAM-co-MAA)-TiO(2) (polymer-TiO(2)) organic-inorganic composite microgels were less thermally sensitive than the polymer gels themselves, owing to rigid O–Ti–O chains introduced into the three-dimensional framework of the polymer microgels. The sizes of the AgNPs and their loading amount were controlled by adjusting the initial concentration of [Ag(NH(3))(2)](+). The surface plasmon resonance (SPR) band of the P(St-NIPAM)/P(NIPAM-co-MAA)-TiO(2)/Ag (polymer-TiO(2)/Ag) composite microgels can be tuned by changing the temperature of the environment. The catalytic activities of the polymer-TiO(2)/Ag composite microgels were investigated in the NaBH(4) reduction of 4-nitrophenol. It was demonstrated that the organic-inorganic network chains of the polymer microgels not only favor the mass transfer of the reactant but can also modulate the catalytic activities of the AgNPs by tuning the temperature.