THERMOTROPIC AQUEOUS GELS AND SOLUTIONS OF N,N-DIMETHYLACRYLAMIDE ACRYLATE COPOLYMERS

Copolymers of N,N-dimethylacrylamide (DMA) with C1-C4 alkyl and alkoxyethyl acrylates-form aqueous solutions with lower critical solution temperatures (LCST) between 0 and 100-degrees-C. As weakly crosslinked gels they exhibit strong cloud points and volume shrinkage with rising temperature. Copolymers of DMA with higher alkyl acrylates are insoluble down to 0-degrees-C, but form hydroplastics and hydrogels with strong cloud points. The LCST is determined by the hydrophobicity and amount of comonomers. The ability of these copolymers to form aqueous solutions with LCSTs can be attributed to a random copolymer structure, which allows an abrupt phase transition from a fully hydrated to a predominantly hydrophobically interacting polymer.