Impact of Polymer Network Inhomogeneities on the Volume Phase Transition of Thermoresponsive Microgels

Abstract

Thermoresponsive polymer gels exhibit pronounced swelling and deswelling upon changes in temperature, rendering them attractive for various applications. This transition has been studied extensively, but only little is known about how it is affected by nano- and micrometer-scale inhomogeneities in the polymer gel network. In this work, droplet microfluidics is used to fabricate microgel particles of strongly varying inner homogeneity to study their volume phase behavior. These particles exhibit very similar equilibrium swelling and deswelling independent of their inner inhomogeneity, but the kinetics of their volume phase transition is markedly different: while gels with pronounced micrometer-scale inhomogeneity show fast and affine deswelling, homogeneous gels shrink slowly and in multiple steps.