Improved Smart Microgel Carriers for Catalytic Silver Nanoparticles
Improved Smart Microgel Carriers for Catalytic Silver Nanoparticles
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DOI：
10.1021/acsomega.8b03511
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发表时间：
2019-03-01
期刊：
影响因子：
4.1
通讯作者：
Hellweg, Thomas
中科院分区：
文献类型：
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作者：
Braendel, Timo;Sabadasch, Viktor;Hellweg, Thomas
在本研究中，基于丙烯酰胺的、具有线性相变区域的温度响应性核壳微凝胶被用作催化活性银纳米颗粒的改进载体。在此背景下，我们通过光子相关光谱、透射电子显微镜和跟踪纳米粒子的表面等离子体共振，研究了聚合物网络中载流子的溶胀行为和纳米银粒子的稳定性。根据微凝胶核心的交联剂含量，我们观察到纳米颗粒在微凝胶网络中非常稳定，当核心交联剂含量为5%和10%时，几周内几乎没有纳米颗粒的出血或聚集。用低温透射电子显微镜研究了溶胀状态下杂化粒子的结构。粒子呈现核壳结构，银纳米粒子主要位于核壳之间的界面。这种结构以前没有使用过，似乎赋予了网络中的纳米颗粒先进的稳定性，并结合了良好的催化活性的可切换性。这是通过跟踪4-硝基苯酚的还原来测量的，这是一个研究得很好的模型反应。所得Arrhenius图表明，与前人的工作类似，核和壳的溶胀会影响银纳米粒子的催化活性。如前所述，核的交联剂含量似乎是催化活性可切换性的一个非常重要的参数。核的交联剂含量越高，载体的溶胀度对银纳米粒子催化活性的影响越大。
Acrylamide-based, thermoresponsive core-shell microgels with a linear phase transition region are used as improved carriers for catalytically active silver nanoparticles in the present study. In this context, we investigated the swelling behavior of the carriers and the stability of the silver nanoparticles inside the polymer network with photon correlation spectroscopy, transmission electron microscopy, and by following the surface plasmon resonance of the nanoparticles. Depending on the cross-linker content of the microgel core, we observed very good stability of the nanoparticles inside the microgel network, with nearly no bleeding or aggregation of the nanoparticles over several weeks for core cross-linker contents of 5 and 10 mol %. The architecture of the hybrid particles in the swollen state was investigated with cryogenic transmission electron microscopy. The particles exhibit a core-shell structure, with the silver nanoparticles located mainly at the interface between the core and shell. This architecture was not used before and seems to grant advanced stability to the nanoparticles inside the network in combination with good switchability of the catalytic activity. This was measured by following the reduction of 4-nitrophenole, which is a well-studied model reaction. The obtained Arrhenius plots show that similar to previous works, the swelling of the core and shell can influence the catalytic activity of the silver nanoparticles. As mentioned before, the cross-linker content of the core seems to be a very important parameter for the switchability of the catalytic activity. A higher cross-linker content of the core seems to be connected to a stronger influence of the carrier swelling degree on the catalytic activity of the silver nanoparticles.