Abstract
We present a novel approach for the preparation of polymer-TiO2 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-TiO2 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)-TiO2 (polymer-TiO2) 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(NH3)2]+. The surface plasmon resonance (SPR) band of the P(St-NIPAM)/P(NIPAM-co-MAA)-TiO2/Ag (polymer-TiO2/Ag) composite microgels can be tuned by changing the temperature of the environment. The catalytic activities of the polymer-TiO2/Ag composite microgels were investigated in the NaBH4 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.
Highlights
The introduction of silver nanoparticles (AgNPs) has attracted significant scientific interest due to their unique optical and electronic properties [1,2,3], remarkable catalytic activities and selectivities [4,5], and significant antibacterial activities [6,7]
The results indicated that reaction times for complete that the catalytic activities of these composites were related to the amounts of AgNPs loaded onto the reduction were 32, 22, 27, 17, and 14 min, at temperatures of 25, 30, 32, 35, and 40 °C, respectively
The results indicated that reaction times for complete reduction were 32, 22, 27, 17, and 14 min, at temperatures of 25, 30, 32, 35, and 40 ◦ C, respectively
Summary
The introduction of silver nanoparticles (AgNPs) has attracted significant scientific interest due to their unique optical and electronic properties [1,2,3], remarkable catalytic activities and selectivities [4,5], and significant antibacterial activities [6,7]. AgNPs are widely used in catalysis [8,9,10], surface-enhanced. AgNPs are generally unstable and aggregated owing to their high surface energies, which limit their application. In order to overcome these shortcomings, researchers usually stabilize AgNPs onto a support material with a different framework structure; this support material increases the specific surface area and improves dispersibility, but it imparts certain functionality to the. Inorganic materials are interesting and promising candidates due to their unique mechanical strengths and stabilities. Used inorganic support materials, such as carbon, silica, alumina, and metal oxides [21,22,23,24], have already been studied extensively
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