Interfacial Adhesive Properties between a Rigid-Rod Pyromellitimide Molecular Layer and a Covalent Semiconductor via Atomistic Simulations
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- 作者：Maxim A. Makeev ; Philippe H. Geubelle ; Nancy R. Sottos ; John Kieffer
- 刊名：ACS Applied Materials & Interfaces
- 出版年：2013
- 出版时间：June 12, 2013
- 年：2013
- 卷：5
- 期：11
- 页码：4702-4711
- 全文大小：670K
- 年卷期：v.5,no.11(June 12, 2013)
- ISSN：1944-8252
文摘
We conducted a comprehensive atomistic simulation study of the adhesive properties of aromatic rigid-rod poly-[(4,4鈥?i>diphenylene) pyromellitimide] on a dimer-reconstructed silicon surface. We describe the structural developments within the adherent鈥檚 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.r>