(576i) Atomic-Level Comparisons of LCST Transition in Thermo-Sensitive Polymers

Stimuli-sensitive polymers due to their ability to respond to changes in surroundings, have a wide range of applications in biotechnology and medicine. Here, we have conducted all-atom molecular dynamics (MD) simulations of three polymers with different lower critical solution temperatures (LCST): Poly(N-isopropylacrylamide) (PNIPAM) (LCST=305K), poly(dimethylaminoethyl methacrylate) (PDMAEMA) (LCST = 323K), and poly(N,N’-diethyl acrylamide) (PDEAAm) (LCST = 299- 308K). Charmm force field was employed to run the simulations. Different sets of charges of the atoms in the charm force field was employed to study their effects on the structure of the polymers. And the MD simulations were conducted below and above the LCST of respective polymers to investigate the origin of their LCSTs. The structural and dynamical properties of the polymers and proximal water were obtained: radius distribution of function (RDF) between water and polymer, radius of gyration (Rg) of polymers, residence time probability of water and free energy.