Mechanics versus thermodynamics: Swelling in multiple-temperature-sensitive core-shell microgels

The thermal transition of a thermoresponsive microgel of poly-N-isopropylacrylamide (PNIPAM; transition temperature =34°C) is shifted to higher temperatures when it is embedded in a shell of temperature-sensitive poly-N-isopropylmethacrylamide (PNIPMAM; transition temperature = 44°C). The magnitude of the shift depends on the shell/core mass ratio. A thick shell induces a third transition arising from strong mechanical forces exerted on the core. (Figure Presented). © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.