Stimuli-Responsive Polymer Surfactants

Various amphiphilic block copolymers (polymer surfactants) possessing hydrophilic and hydrophobic segments were designed, prepared, and examined for stimuli-responsive selforganization in water. New polymer micelles or physical gels that would have this property were made by intermolecular hydrophobic interaction. Recent advances and related topics are initially summarized in this paper. Well-controlled block copoly (vinyl ether) s were synthesized in this study by living cationic polymerization of vinyl ethers with various functional groups. Not only hydrophilic polyalcohols and hydrophobic poly (alkyl vinyl ether) s, but thermally-responsive polymers with oxyethylene units as well were used as segments of diblock copolymers. When aqueous polymer solution was heated, characteristic physical gelation occurred in a certain temperature range corresponding to the particular properties of the segments. As other stimuli, the addition of selected organic compounds and H+ to the solution containing diblock copolymers was also examined as a means for obtaining physical gels via a mechanism similar to that in thermally-responsive systems.