Hydrophobically modified acrylamide-based hydrogels

The synthesis of acrylamide based hydrogels incorporating a small proportion of hydrophobic functional groups results in a hydrogel structure with improved mechanical properties. In particular increased mechanical toughness and tensile strength whilst maintaining a relatively high swelling ratio. A method of increasing toughness has been developed by introducing a number of long alkyl chain hydrophobic groups into the hydrophilic structure. These hydrophobic groups create domains of densely clustered polymer chains within the highly swollen hydrogel matrix. Single edged notch tensile tests demonstrate a significant increase in fracture energy when the hydrophobes are able to interact in aqueous solutions compared to gels swollen in organic solvents in which the hydrophobes act independently. Therefore it is speculated that these domains increase energy dissipation around the crack tip during fracture causing an increase in mechanical toughness.