Intelligent Hydrogels Via Gamma-Ray Induced Polymerization of Micellar Monomer Solutions and Microemulsions

Summary: Intelligent hydrogels were prepared upon polymerization of micellar aqueous comonomer solutions and microemulsions containing the cationic surfactant monomer 11-acryloyloxyundecyltrimethylammonium bromide (AUTMAB) and N-isopropylacrylamide (NIPAM). A chemically and physically cross-linked network structure is formed consisting of blocks of P-NIPAM and P-AUTMAB. The P-AUTMAB blocks act as physical cross-linking units improving the mechanical stability of the gel. While pure P-NIPAM hydrogels are disrupted under low compression, gels polymerized from micellar solution or microemulsion can be reversibly compressed. The presence of AUTMAB in the gel increases the swelling up to a factor of 30 compared with the pure P-NIPAM gel. Rapid and reversible swelling is observed for hydrogels with an AUTMAB content up to 2.5 wt.-%.