College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing100029, China.
Langmuir. 2023 Feb 14;39(6):2408-2421. doi: 10.1021/acs.langmuir.2c03236. Epub 2023 Feb 1.
Stimuli-responsive hybrid nanoparticles used for controllable catalysis have been attracting increasing attention. This study aims to prepare hybrid microgels with excellent temperature-sensitive colorimetric and catalytic properties through combining the surface plasmon resonance properties of gold nanoparticles (AuNPs) with the temperature-sensitive properties of poly(-isopropylacrylamide) (PNIPAM)-based microgels. Microgels with hydroxy groups (MG-OH) were prepared by soap-free emulsion polymerization, using -isopropylacrylamide as the main monomer, hydroxyethyl methylacrylate as the functional monomer, ,'-methylene bisacrylamide as the crosslinker, and 2,2'-azobis(2-methylpropionamidine) dihydrochloride as an initiator to ensure the microgels are positively charged. Furthermore, chemical modification on the surface of MG-OH was carried out by 3-mercaptopropyltriethoxysilane to obtain thiolated microgels (MG-SH). Two kinds of hybrid nanoparticles, AuNPs@MG-OH and AuNPs@MG-SH, were self-assembled, through electrostatic interaction between positive MG-OH and negative citrate-stabilized AuNPs as well as through synergistic bonding of electrostatic interaction and Au-S bonding between positive MG-SH and negative AuNPs. The morphology, stability, temperature-sensitive colorimetric properties, and catalytic properties of hybrid microgels were systematically investigated. Results showed that although both AuNPs@MG-OH and AuNPs@MG-SH exhibit good temperature-sensitive colorimetric properties and controllable catalytic properties for the reduction reaction of p-nitrophenol, AuNPs@MG-SH with synergistic bonding has better stability and higher catalytic performance than AuNPs@MG-OH. This work has good competitiveness against known PNIPAM-based materials and may provide an effective method for preparing smart catalysts by self-assembly with stimuli-responsive polymers, which has a great potential application for catalyzing a variety of reactions.
用于可控催化的响应性杂化纳米粒子受到越来越多的关注。本研究旨在通过结合金纳米粒子（AuNPs）的表面等离子体共振特性和基于聚（异丙基丙烯酰胺）（PNIPAM）的微凝胶的温度敏感性，制备具有优异的温度敏感比色和催化性能的杂化微凝胶。通过无皂乳液聚合制备了具有羟基的微凝胶（MG-OH），以异丙基丙烯酰胺为主单体，羟乙基甲基丙烯酸酯为功能单体， ，'-亚甲基双丙烯酰胺为交联剂，2,2'-偶氮双（2-甲基丙脒）二盐酸盐为引发剂，以确保微凝胶带正电。此外，通过 3-巯丙基三乙氧基硅烷对 MG-OH 的表面进行化学修饰，得到巯基化微凝胶（MG-SH）。通过带负电的柠檬酸稳定的 AuNPs 与带正电的 MG-OH 之间的静电相互作用以及带正电的 MG-SH 与带负电的 AuNPs 之间静电相互作用和 Au-S 键的协同键合，自组装了两种杂化纳米粒子，AuNPs@MG-OH 和 AuNPs@MG-SH。系统研究了杂化微凝胶的形态、稳定性、温度敏感比色性能和催化性能。结果表明，虽然 AuNPs@MG-OH 和 AuNPs@MG-SH 均表现出良好的温度敏感比色性能和对 p-硝基苯酚还原反应的可控催化性能，但具有协同键合的 AuNPs@MG-SH 比 AuNPs@MG-OH 具有更好的稳定性和更高的催化性能。这项工作对已知的基于 PNIPAM 的材料具有很好的竞争力，可能为通过与响应性聚合物自组装制备智能催化剂提供一种有效的方法，在催化各种反应方面具有很大的应用潜力。
