Abstract
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.
Original language | English |
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Pages (from-to) | 1235-1239 |
Number of pages | 5 |
Journal | ACS Macro Letters |
Volume | 3 |
Issue number | 12 |
Early online date | 17 Nov 2014 |
DOIs | |
Publication status | Published - 16 Dec 2014 |