Upon heating above their lower critical solution temperature (LCST) poly[oligo(ethyleneglycol)methacrylate]s (POEGMA) were shown to undergo a shift in their partition coefficient triggering aqueous to organic phase transfer, which indicated their potential to partition into cell membranes upon application of an external stimulus. Fluorescence-based assays indicated that the LCST transition did not induce lysis of model phospholipid vesicles but did promote fusion, as confirmed by dynamic light scattering. Membrane perturbation assays and linear dichroism spectroscopy investigations suggest that POEGMAs above their transition temperatures can interact with, or insert into, membranes. These findings will help develop the application of responsive polymers in drug delivery.