Stimuli-Responsive Poly[oligo(ethylene glycol) methacrylate] Monolayers: Reversible Temperature-Driven Swelling...

Stimuli-responsive polymers, which can reversibly change their physicochemical properties in response to external stimuli, have broad potential applications in biomedical and surface engineering. Here, we report the synthesis of hydrophilic poly-[oligo-(ethylene glycol) methacrylate] [p-(DEGMA-co-OEG₅MA)] copolymers with tunable lower critical solution temperatures (LCSTs). Copolymers with LCST values near physiological temperature were synthesized via controlled radical polymerization, end-functionalized with thiol groups, and immobilized onto gold substrates to form thermoresponsive monolayers. Real-time quartz crystal microbalance with dissipation (QCM-D) and spectroscopic ellipsometry measurements revealed reversible temperature-dependent swelling and contraction of the monolayers. To the best of our knowledge, this is the first demonstration of the direct formation of hydrophilic p-(DEGMA-co-OEG₅MA) monolayers on gold QCM-D sensors. The monolayers exhibited excellent protein-repelling properties against bovine serum albumin, confirming their antifouling behavior. These findings demonstrate a controllable strategy for fabricating biocompatible, thermoresponsive, and antifouling polymer interfaces with strong potential for biosensing, medical device coatings, and controlled drug delivery applications.