Core-shell microgels as thermoresponsive carriers for catalytic palladium nanoparticles.
Core-shell microgels as thermoresponsive carriers for catalytic palladium nanoparticles.
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DOI：
10.1039/d0sm00433b
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发表时间：
2020-06
期刊：
影响因子：
3.4
通讯作者：
Viktor Sabadasch;Lars Wiehemeier;T. Kottke;T. Hellweg
中科院分区：
文献类型：
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作者：
Viktor Sabadasch;Lars Wiehemeier;T. Kottke;T. Hellweg
具有响应性的核壳微凝胶是稳定钯纳米粒子和控制其催化活性的很有前途的体系。在这里，聚-N-正丙基丙烯酰胺(PNNPAM)与甲基丙烯酸共聚得到微凝胶核心粒子，然后在其表面包裹一层无酸的聚-N-异丙基甲基丙烯酰胺(PNIPMAM)外壳。核壳系统和核壳系统都被用作pH和温度响应性载体系统，用于钯纳米颗粒的掺入。包埋的纳米粒子具有均匀的尺寸分布，直径在20 nm左右。通过UV-Vis光谱跟踪对硝基苯酚还原成对氨基苯酚的动力学过程，考察了它们的催化活性。对于PNNPAM微凝胶芯，速率常数的温度依赖关系符合Arrhenius方程，这对于热敏载体系统来说是一种不寻常的行为，但对于被动系统(如聚电解质刷子)来说却很常见。相反，包埋在微凝胶核壳体系中的纳米粒子在PNIPMAM壳层的体积相变温度(44℃)时催化活性急剧下降。因此，成功地实现了一种有前景的被动纳米粒子载核和热响应壳层结构。
Responsive core-shell microgels are promising systems for a stabilization of Pd nanoparticles and control of their catalytic activity. Here, poly-N-n-propylacrylamide (PNNPAM) was copolymerized with methacrylic acid to yield microgel core particles, which were subsequently coated with an additional, acid-free poly-N-isopropylmethacrylamide (PNIPMAM) shell. Both core and core-shell systems were used as pH- and temperature-responsive carrier systems for the incorporation of palladium nanoparticles. The embedded nanoparticles were found to have a uniform size distribution with diameters at around 20 nm. Their catalytic activity was investigated by following the kinetics of the reduction of p-nitrophenol to p-aminophenol using UV-vis spectroscopy. For the PNNPAM microgel core, the temperature dependence of the rate constant followed the Arrhenius equation, which is an unusual behaviour for thermoresponsive carrier systems but common for passive systems such as polyelectrolyte brushes. In contrast, the catalytic activity of nanoparticles embedded in microgel core-shell systems decreased drastically at the volume phase transition temperature (44 °C) of the PNIPMAM shell. Accordingly, a promising architecture of passive nanoparticle-carrying core and thermoresponsive shell was realized successfully.