UCST‐Responsive PMEGA: From Solution Behavior to Functional Hydrogel Surfaces

ABSTRACT Thermoresponsive polymer coatings have attracted considerable attention for applications in materials science, biotechnology, and surface engineering. Materials exhibiting upper critical solution temperature (UCST) behavior remain comparatively underexplored in comparison to lower critical solution temperature (LCST), particularly in the form of structured thin films. The present work illustrates the use of poly(2‐(methacryloyloxy)ethylureido glycinamide) (PMEGA) as a versatile UCST‐responsive platform for the fabrication of surface‐attached hydrogel coatings with controlled architecture and functionality. This polymer, with straightforward monomer synthesis, exhibits a well‐defined UCST transition in aqueous solution. Based on thiol–ene click chemistry, the herein presented strategy displays the tunable engineering of homogeneous and microstructured hydrogel films by the cross‐linking and grafting (CLAG) approach. This method enables the fabrication of hydrogel coatings with precisely controlled thicknesses, as well as the generation of well‐defined micropatterns via UV‐induced photolithography like for photoresist. Importantly, the thermoresponsive swelling behavior of the surface‐grafted hydrogels can be adjusted by adjusting UV irradiation parameters, providing direct control over the UCST response in confined geometries. Overall, the combination of straightforward polymer synthesis, scalable thin‐film processing, and tunable thermo‐responsive properties opens new opportunities for the development of advanced functional coatings and microstructured surfaces.