Pongsanon Palida, Kawamura Akifumi, Kawasaki Hideya, Miyata Takashi
Department of Chemistry and Materials Engineering, Kansai University, Suita, Osaka 564-8680, Japan.
Organization for Research and Development of Innovative Science and Technology, Kansai University, Suita, Osaka 564-8680, Japan.
Gels. 2024 May 22;10(6):357. doi: 10.3390/gels10060357.
Gold nanoparticles (AuNPs) possess attractive electronic, optical, and catalytic properties, enabling many potential applications. Poly(-isopropyl acrylamide) (PNIPAAm) is a temperature-responsive polymer that changes its hydrophilicity upon a slight temperature change, and combining PNIPAAm with AuNPs allows us to modulate the properties of AuNPs by temperature. In a previous study, we proposed a simpler method for designing PNIPAAm-AuNP hybrid microgels, which used an AuNP monomer with polymerizable groups. The size of AuNPs is the most important factor influencing their catalytic performance, and numerous studies have emphasized the importance of controlling the size of AuNPs by adjusting their stabilizer concentration. This paper focuses on the effect of AuNP size on the catalytic activity of PNIPAAm-AuNP hybrid microgels prepared via the copolymerization of -isopropyl acrylamide and AuNP monomers with different AuNP sizes. To quantitatively evaluate the catalytic activity of the hybrid microgels, we monitored the reduction of 4-nitrophenol to 4-aminophenol using the hybrid microgels with various AuNP sizes. While the hybrid microgels with an AuNP size of 13.0 nm exhibited the highest reaction rate and the apparent reaction rate constant () of 24.2 × 10 s, those of 35.9 nm exhibited a small of 1.3 × 10 s. Thus, the catalytic activity of the PNIPAAm-AuNP hybrid microgel was strongly influenced by the AuNP size. The hybrid microgels with various AuNP sizes enabled the reversibly temperature-responsive on-off regulation of the reduction reaction.
金纳米颗粒（AuNPs）具有吸引人的电子、光学和催化性能，使其具有许多潜在应用。聚（N-异丙基丙烯酰胺）（PNIPAAm）是一种温度响应性聚合物，在温度稍有变化时就会改变其亲水性，将PNIPAAm与AuNPs结合可使我们通过温度来调节AuNPs的性能。在先前的一项研究中，我们提出了一种设计PNIPAAm-AuNP杂化微凝胶的更简单方法，该方法使用带有可聚合基团的AuNP单体。AuNPs的尺寸是影响其催化性能的最重要因素，许多研究都强调了通过调节其稳定剂浓度来控制AuNPs尺寸的重要性。本文重点研究了AuNP尺寸对通过N-异丙基丙烯酰胺与不同AuNP尺寸的AuNP单体共聚制备的PNIPAAm-AuNP杂化微凝胶催化活性的影响。为了定量评估杂化微凝胶的催化活性，我们使用具有各种AuNP尺寸的杂化微凝胶监测了4-硝基苯酚还原为4-氨基苯酚的过程。当AuNP尺寸为13.0 nm的杂化微凝胶表现出最高的反应速率和24.2×10⁻³ s⁻¹的表观反应速率常数（k）时，35.9 nm的杂化微凝胶表现出较小的k值，为1.3×10⁻³ s⁻¹。因此，PNIPAAm-AuNP杂化微凝胶的催化活性受AuNP尺寸的强烈影响。具有各种AuNP尺寸的杂化微凝胶能够实现还原反应的可逆温度响应开-关调节。
