Recyclable l-Proline Functional Nanoreactors with Temperature-Tuned Activity Based on Core-Shell Nanogels.
Recyclable l-Proline Functional Nanoreactors with Temperature-Tuned Activity Based on Core-Shell Nanogels.
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DOI：
10.1021/mz500704y
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发表时间：
2014-11
影响因子：
5.8
通讯作者：
Annhelen Lu;Dafni Moatsou;I. Hands-Portman;Deborah A. Longbottom;R. O’Reilly
中科院分区：
文献类型：
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作者：
Annhelen Lu;Dafni Moatsou;I. Hands-Portman;Deborah A. Longbottom;R. O’Reilly
通过种子沉淀聚合工艺合成了基于含 l-脯氨酸的疏水核和热响应性聚（N-异丙基丙烯酰胺）（PNIPAM）壳的可回收核壳（CS）纳米凝胶。使用动态光散射（DLS）和透射电子显微镜（TEM）验证壳的成功添加并研究纳米结构的热响应特性。在不对称羟醛反应模型中评估了纳米凝胶的催化活性，由于 PNIPAM 壳的疏水性，随着温度的升高观察到催化活性增强。然而，当基于电晕（GS）交联密度梯度合成具有核-壳形态的纳米凝胶时，在高温下观察到活性急剧下降：外部轻度交联的“电晕”聚合物链的崩溃似乎阻碍了对催化核心的访问。在多次回收和再利用循环中保持了高活性和对映选择性，凸显了这些催化纳米结构的回收潜力。
Recyclable core-shell (CS) nanogels based on l-proline-containing hydrophobic cores with a thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) shell have been synthesized via a seeded precipitation polymerization process. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to verify the successful addition of the shell and investigate the thermoresponsive properties of the nanostructures. The catalytic activity of the nanogels was assessed in a model asymmetric aldol reaction, where an enhancement was observed with increasing temperature, attributed to the hydrophobic nature of the PNIPAM shell. However, when a nanogel was synthesized with core-shell morphology based on a gradient of cross-linking density in the corona (GS), a dramatic drop in activity was observed at elevated temperatures: the collapse of the outer, lightly cross-linked, "corona" polymer chains appears to block access to the catalytic core. High activity and enantioselectivity were maintained in a number of recovery and reuse cycles, highlighting the recycling potential of these catalytic nanostructures.