Hydrogels prepared by copolymerization of poly(ethylene oxide) macromonomers with hydrophilic and hydrophobic methacrylates

A number of amphiphilic hydrogels were obtained by the free-radical copolymerization of poly(ethylene oxide) bis(macromonomer) containing methacrylate end groups with small hydrophilic and hydrophobic methacrylates. It is shown that the addition of 2-hydroxyethyl methacrylate increases the degree of gel swelling in water by 20-25%; this effect seems to be due to the enhanced hydrophilicity of network junctions. The values of elastic modulus G and the character of their correlation with the swelling degree Q suggest that the number of elastically active chains in the network remains unchanged, but the conformational state and elasticity of chains are closer to values typical of Gaussian networks compared to their analogs without any additives. The crosslink density of networks containing n-butyl methacrylate as a comonomer decreases, their swelling in water improves, and a competition between a hydrophobic (network junctions) and hydrophilic (PEO chains) components results in the nonmonotonous dependence of swelling on the composition of a water-alcohol mixture.