The interfacial behavior of water/PMMA thin film under normal compression.

Molecular dynamics simulation (MD) has been used to investigate the structure property of water/PMMA interface under compression and compression release. A virtual repulsive wall was employed to generate a normal compression strain on the simulation model, leading a compressive system. In order to understand the difference of interfacial phenomenon between the system under strain and under release, the hydrogen bond and density distributions of water and PMMA along the normal direction are calculated. The results show that the hydrogen bond distribution profile of compressive system is different from that of the release system at the same strain. It demonstrates that the characteristic structure of water/PMMA interface under a compression-release cycle is not reversible.