Solvent Induced Inversion of Core–Shell Microgels

Abstract

The morphology of\ncore–shell microgels under different swelling\nconditions and as a function of the core–shell thickness ratio\nis systematically characterized by mesoscale hydrodynamic simulations.\nWith increasing hydrophobic interaction of the shell polymers, we\nobserve drastic morphological changes from a core–shell structure\nto an inverted microgel, where the core is turned to the outside,\nor a microgel with a patchy surface of core polymers directly exposed\nto the environment. We establish a phase diagram of the various morphologies.\nMoreover, we characterize the polymer and microgel conformations.\nFor sufficiently thick shells, the changes of the shell size upon\nincreasing hydrophobic interactions are well described by the Flory–Rehner\ntheory. Additionally, this theory provides a critical line in the\nphase diagram separating core–shell structures from the distinct\ntwo other phases. The appearing new phases provide a novel route to\nnano- and microscale functionalized materials.