De-Swelling Mechanisms of a Surface-Grafted Poly(NIPAAm) Brush

In this study, we investigated the deswelling mechanisms of hydrated surface-grafted poly(N-isopropylamide) (P(NIPAAm)) brush using full-atomistic molecular dynamics (MD) simulations at various temperatures such as 275, 290, 320, 345, and 370K. We clearly observed the deswelling of the P(NIPAAm) brush above the lower critical solution temperature (305K) below which the P(NIPAAm) brush is associated with water molecules stably. By analyzing the density profiles, the pair correlation functions & the coordination number, hydrogen bonding, solvent accessible surface area, and the free energy change of system, we explain that the detail mechanisms of deswelling of P(NIPAAm) brush above LCST.