The Interface Between Platinum(111) and Poly(vinyl Alcohol) Melt: A Molecular Dynamics Study

Abstract

A Molecular dynamics simulations are used to study the structure and dynamics of the platinum(111)/poly(vinyl alcohol) (PVA) oligomers (10 monomers long) interface at 400 K. The mass density and number density distribution of separate atoms along the surface normal resemble, in general, the distributions obtained for the platinum(111)/ liquid isopropanol interface (28). The small discrepancies are dictated by the chemical bonds between monomers within PVA chains. The differences between PVA and isopropanol in the orientational structure of O-H and O-C bond vectors are large immediately at the platinum surface. The connectivity of monomers within PVA chains is also the main driving force of these changes. At longer distances, the structure of the PVA melt resembles approximately that of liquid isopropnaol. The PVA chains, which are directly adsorbed on the surface, extend into the bulk up to 2.25 nm. There exists a region where adsorbed chains mix with nonadsorbed ones and, therefore, form very likely hydrogen bonds between each other. Thus, it is expected that PVA melt, unlike liquid isopropanol, attaches relatively strongly onto the metal surface.

Treatment of electrostatic interactions in simulations of the interface between transition metal surfaces and organic matter: the discrete classical model and the reaction-field dielectric method

“…7,8 Since the RFD is much faster than the DCM, it becomes possible to study the interface between the Pt(111) surface and the melt of short poly(vinyl alcohol) (PVA) oligomers via molecular dynamics simulations. 3 An important correction to our previous study of the Pt(111)/isopropanol interface using the DCM is also discussed here.…”

“…In order to estimate the properties of real polymeric materials and, in particular, of polymer/solid (metal) interfaces via molecular simulations, large sizes and time scales must be used. The relaxation times for systems of even short oligomers in a melt are extremely long, 2,3 if compared to simple fluids or gases. Therefore, molecular simulations of polymeric materials and polymer/solid (metal) interfaces require a lot of computational resources.…”

“…For simulations performed using the DCM to calculate the electrostatic forces, the polarizability of platinum atoms a was set equal to 0.001835 nm 3 . For simulations that used the reaction-field dielectric method (RFD), the value of the dielectric constant of isopropanol (19.92) was used.…”