Abstract
Poly(N-acryloyl glycinamide) is a well-known thermoresponsive polymer possessing an upper critical solution temperature (UCST) in water. By copolymerizing N-acryloyl glycinamide (NAGA) with methacrylic acid (MAA) in the presence of a crosslinker, poly(N-acryloyl glycinamide-co-methacrylic acid) [P(NAGA–MAA)] copolymer microgels with an MAA molar fraction of 10–70 mol % were obtained. The polymerization kinetics suggests that the copolymer microgels have a random structure. The size of the microgels was between 60 and 120 nm in the non-aggregated swollen state in aqueous medium and depending on the solvent conditions, they show reversible swelling and shrinking upon temperature change. Their phase transition behavior was studied by a combination of methods to understand the process of the UCST-type behavior and interactions between NAGA and MAA. P(NAGA–MAA) microgels were loaded with silver nanoparticles (AgNPs) by the reduction of AgNO3 under UV light. Compared with the chemical reduction of AgNO3, the photoreduction results in smaller AgNPs and the amount and size of the AgNPs are dependent on the comonomer ratio. The catalytic activity of the AgNP-loaded microgels in 4-nitrophenol reduction was tested.
Highlights
Responsive microgels[1,2] loaded with inorganic nanoparticles have gained much research interest for catalysis applications.[3−14] These hybrid microgels display enhanced catalytic performance, for example, due to the improved stability of the nanoparticles within the polymer networks, tunability of the catalytic properties, and recyclability of the catalyst by utilizing the stimuli-responsivity of the microgels
Most studies are concentrated on the use of lower critical solution-type (LCST) microgels, especially poly(N-isopropyl acrylamide) (PNIPAM)
A set of microgels varying the ratio of N-acryloyl glycinamide (NAGA) and methacrylic acid (MAA) monomers was prepared by free radical polymerization
Summary
Responsive microgels[1,2] loaded with inorganic nanoparticles have gained much research interest for catalysis applications.[3−14] These hybrid microgels display enhanced catalytic performance, for example, due to the improved stability of the nanoparticles within the polymer networks, tunability of the catalytic properties, and recyclability of the catalyst by utilizing the stimuli-responsivity of the microgels. To determine the phase transition behavior of the microgels, they were first dispersed in neutral water at a 10 mg/mL concentration and observed at room temperature, Figure 3.
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