New insights into adsorption structure and hydration of polymer at oil-water interface obtained by molecular dynamics simulations: Isotactic poly(methacrylic acid)

Abstract

We have performed atomistic MD simulations to investigate structure and hydration properties of isotactic Poly(methacrylic acid) (i-PMA) at CCl4–H2O interface at different concentration up to monolayer coverage. Three concentration regimes dilute, semi-dilute and concentrated are shown to occur at molecular level detail for the first time for polymer systems at oil-water interface. i-PMA chains at low interface concentration exists in a planar conformation along with an ordered arrangement of side groups and changes to a random coil structure at high concentration, which is observed from the variation of components of Rg and decrease in preferential orientation of groups. An abrupt change in chain conformation marks the end of the dilute regime and a rapid increase in thickness of adsorbed layer marks the beginning of the concentrated regime. This study provides new molecular insights into conformational changes and the associated changes in interactions among different chemical groups with variation of the interface concentration of polymer.