Interfacial adhesive properties between a rigid-rod pyromellitimide molecular layer and a covalent semiconductor via atomistic simulations

Maxim A. Makeev, Philippe H Geubelle, Nancy R Sottos, John Kieffer

Research output: Contribution to journalArticlepeer-review

Abstract

We conducted a comprehensive atomistic simulation study of the adhesive properties of aromatic rigid-rod poly-[(4,4′diphenylene) pyromellitimide] on a dimer-reconstructed silicon surface. We describe the structural developments within the adherent's interfacial region at the atomistic scale, and evaluate the energetics of the adhesive interactions between bimaterial constituents. In particular, we observe a transition between noncontact and contact adhesion regimes as a function of the interfacial bonding strength between the polyimide repeat units and the silicon substrate. This transition is manifest by a three- to four-fold increase in adhesive energy, which is entirely attributable to structural relaxation in the organic layer near the interface, revealing the importance of accurately describing structural details at interfaces for reliable interfacial strength predictions. The underlying molecular reconfigurations in the pyromellitimide layer include preferred orientation of the rigid-rod molecules, molecular stacking, ordering, and the local densification. The role of each of these factors in the adhesive behavior is analyzed and conclusively described. Where possible, simulation results are compared with theoretical model predictions or experimental data.

Original languageEnglish (US)
Pages (from-to)4702-4711
Number of pages10
JournalACS Applied Materials and Interfaces
Volume5
Issue number11
DOIs
StatePublished - Jun 12 2013

Keywords

  • adhesion
  • glass transition
  • interface
  • molecular dynamics
  • polyimide
  • structure-property relations

ASJC Scopus subject areas

  • Materials Science(all)

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