WETTING OF CRYSTALLINE POLYMER SURFACES - A MOLECULAR-DYNAMICS SIMULATION

Molecular dynamics has been used to study the wetting of model polymer surfaces, the crystal surfaces of polyethylene (PE), poly(tetrafluoro ethylene) (PTFE), and poly(ethylene terephthalate) (PET) by water and methylene iodide. In the simulation a liquid droplet is placed on a mo del surface and constant temperature, rigid body molecular dynamics is carried out while the model surface is kept fixed. A generally define d microscopic contact angle between a liquid droplet and a solid surfa ce is quantitatively calculated from the volume of the droplet and the interfacial area between the droplet and the surface. The simulation results agree with the trend in experimental data for both water and m ethylene iodide. The shape of the droplets on the surface is analyzed and no obvious anisotropy of the droplets is seen in the surface plane , even though the crystal surfaces are highly oriented. The surface fr ee energies of the model polymer surfaces are estimated from their con tact angles with the two different Liquid droplets. (C) 1995 American Institute of Physics.