Simultaneous crosslinking induces macroscopically phase-separated microgel from a homogeneous mixture of multiple polymers

Abstract

This paper reports a unique phase separation behavior, a simultaneous-crosslinking-driven phase separation in co-gelation (SPSiC) core-shell microgel that spontaneously forms from a homogeneous pre gel solution of multiple polymers. The SPSiC microgel, composed of an alginate shell and an N- isopropylacrylamide (NIPAM) core, were synthesized by a single fabrication step wherein a mixed pre-gel solution of sodium alginate and NIPAM monomer was ejected by centrifugation with photo polymerization and ion crosslinking instantaneously. Phase separation was modeled by varying the degree of polymerization and the size of the polymer chain. Moreover, an implantable, multi-functional drug delivery system combined with a transdermal glucose sensor was demonstrated with core-shell Janus SPSiC microgels. This work shows a macroscopic phase separation behavior, which occurs during the gelation process, and also provides a simple and unique methodology to create multifunctional bio-microprobes. (c) 2021 Elsevier Ltd. All rights reserved.