Poly(ethylene glycol)-Containing Cationic Hydrogels with Lipophilic Character

Not much effort has been focused towards the development of hydrogels that swell in nonpolar solvents. We have synthesized a new set of polyelectrolyte hydrogels and demonstrated their ability to absorb a less-polar or nonpolar organic solvent, as well as their ability to resist gel-collapse in a predominantly nonpolar medium. The hydrogels were prepared by free radical polymerization of different molar ratios of poly(ethylene glycol) methyl ether acrylate and (3-(methacryloylamino)propyl)-trimethyl ammonium chloride as comonomers in an aqueous medium. Their swelling behavior in organic solvents was studied by varying the dielectric constant of the swelling medium including mixed-solvent systems. Besides a high degree of swelling (up to 200 times) in polar solvents, some of the hydrogels also exhibited moderate swelling (up to 15 times) in less-polar organic solvents. Hydrogels samples with high cationic content showed drastic change in swelling extent in some of the mixed-solvent systems. It was also interesting to note that the retention of significant swelling in dimethyl sulphoxide-toluene mixture with even 90% toluene content for some compositions. These polyelectrolyte hydrogels with improved lipophilicity opens up greater opportunities for the development of even superior soft materials through proper structural optimizations that would successfully function for a wider range of solvents. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39873.