Atomistic insight into the role of amine groups in thermoresponsive poly(2-dialkylaminoethyl methacrylate)s

The role of amine groups in the phase separation of thermoresponsive poly(2-dialkylaminoethyl methacrylate)s with dimethyl-, diethyl-, and diisopropylaminoethyl substituents has been studied by atomistic molecular dynamics simulations. The polymer chains present a more compact conformation at higher temperatures, losing contact with the water molecules. In the vicinity of the amine groups, the exclusion of water molecules increases with the increasing hydrophobicity of the amine moieties above the lower critical solution temperature. In particular, the potential of mean force results suggest that the formation of hydrogen bonding between the amine groups and water molecules involves more entropic contributions at higher temperatures in the cases of the diethylaminoethyl and diisopropylaminoethyl groups. These results provide insight for the rational design of side chains of thermoresponsive polymers for smart materials and devices.