The nature of the interactions of poly(methyl methacrylate) oligomers with an aluminum surface

Abstract

Incubation: Subthreshold ablation of poly-(methyl methacrylate) and the nature of the decomposition pathways Polymer-metal interfaces are of increasing technological importance in a variety of applications. These interfaces are characterized by specific interactions between functional _ groups of the organic polymer and the metallic substrate. In order to study the structure of these interfaces at the molecular level, the energetics of the segment-surface interactions must be well characterized. We have used density functional theory to investigate the interactions of poly(methyl methacrylate) (PMMA) oligomers with aluminum surfaces. The aluminum surface is represented by the simple jellium model. The energetics of the interactions between the organic molecules and the aluminum surface are calculated as a function of the orientation with respect to the surface of the organic molecule and various internal degrees of freedom. The computed energy hypersurfaces exhibit a rich structure characterized by several energy minima and barriers. Implications of such an energy hypersurface for the architecture of long chain molecules at the interface are discussed. The energy hypersurfaces also show that the rotational conformational statistics of PMMA interacting with an aluminum surface should be quite different from that of bulk PMMA. The reported energy hypersurfaces have been used to construct an empirical force-field for future molecular simulations oflong chains subject to the proper potentials.

Non-equilibrium in adsorbed polymer layers

“…The form of k(s) corresponding to theta solvent solutions was substituted into the master equation describing the evolution of the chain's loop distribution. Electronic structure calculations [189] indicated enhanced reaction rates for monomers neighboring a graft point. Due to this local cooperative effect, the numerical solution of the master equation led to a process of chain zipping onto the surface growing outwards from the first attachments.…”

Irreversible adsorption from dilute polymer solutions

“…It was found that the chain adsorbs in a zipping mechanism the origin of which was greatly enhanced reactivities for monomers neighboring a graft point. These reactivities were taken as greatly enhanced on the basis of electronic structure calculations [82,83].…”

Non-bonded force field for the interaction between metals and organic molecules: a case study of olefins on aluminum

“…Unfortunately, similarly realistic descriptions for the non-bonded interactions between organic molecules and metal atoms are not generally available, despite some progress: for example, Shaffer et al have proposed an orientation-dependent functional for the interaction between poly(methyl methacrylate) and aluminum atoms. 21 Fartaria et al have derived a united atom model based on density functional theory (DFT) calculations for the simulating of ethanol adsorption on Au(111) surfaces. 22 Zerbetto and collaborators have adopted an atomic based empirical FF to describe the interaction between alkane and Au(111) surfaces.…”