Tuning network structures of hydrophobic hydrogels by controlling polymerization solvent

Abstract

Hydrophobic copolymer hydrogels hold great promise for various functional applications; however, the influence of monomer distribution and the resulting network structures on hydrogel properties remains largely unexplored. Here, hydrophobic hydrogels were synthesized through free-radical copolymerization using equimolar cationic and fluorous monomers. By employing precursor solutions with different solvent qualities, hydrogels with diverse copolymer network phase behaviors, varying from homogeneous networks to phase-separated structures, were obtained. The hydrophilicity disparity between monomers, coupled with their distribution in networks, dictates the hydrogel properties. Statistical copolymer hydrogels demonstrated swelling behaviors in both water and organic solvents, whereas phase-separated hydrogels exhibited anti-swelling behaviors. Moreover, statistical copolymer hydrogels equilibrated in saltwater showed superior mechanical strength and fracture energy compared to the phase-separated hydrogels. These findings underscore the pivotal role of monomer distribution in controlling copolymer hydrogel properties, providing a promising avenue for the design of hydrogel materials.