Computation of surface energy and surface segregation phenomena of perfluorinated copolymers and blends – A molecular modeling approach

Abstract

In this paper, we studied the surface properties and surface segregation phenomena of perflourinated copolymers and blends using molecular mechanics (MM) and molecular dynamics (MD) simulation in the NVT ensemble. The importance of functional group, 1H, 1H-dihydroperfluorohendecyl methacrylate (F10MA) and their surface preference over polymer backbone segments viz., methyl methacrylate (MMA) has been investigated. We have shown that degree of blockiness and change in chain architecture have significant effects on surface energy values. Surface energy differences between MMA and F10MA segments have been asserted by introducing a surface critical parameter, χ_s. Computations have been carried out to obtain bulk properties like cohesive energy density (CED) and solubility parameter (δ) by performing MM and MD simulations. Surface energies of MMA/F10MA blends have been computed by bulk pressure–volume–temperature (PVT) properties. Molecular dynamics simulation using NPT ensemble has been used to obtain specific volume as a function of temperature for different compositions of MMA/F10MA blends. From these results and using the equation of state approaches, thermal expansion coefficient has been obtained to calculate PVT parameters. These surface energy values compare well with the surface energy data calculated by the Zisman equation. Finally, the surface-enrichment behavior of F10MA components in the blend has been examined.