Interfacial Adhesive Properties between a Rigid-Rod Pyromellitimide Molecular Layer and a Covalent Semiconductor via Atomistic Simulations

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.

Investigation of the interface between polyethylene and functionalized graphene: A computer simulation study

“…The dynamic simulations were run for 500 ps at all temperatures lower than 300 K. After a 15 ns simulation at 300 K, the dynamic simulations were run for 1 ns at all intermediate temperatures up to 500 K. The equilibration typically requires long simulation times at lower temperatures. Therefore, the temperature was increased to 500 K M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 12 to accelerate the equilibration process in this study. The dynamics simulation was carried out at 500 K for 10 ns to achieve system equilibration.…”

“…Then, the interplay between the change in structural and the associated dynamic properties in the interphase was compared with the bulk polymer. The work of adhesion between polyimide and silicon surface was evaluated by Makeev et al [12]. The observation of a transition between noncontact and contact adhesion regimes as a function of the interfacial bonding strength was attributed to structural relaxation in the organic layer near the interface.…”

Dependence of Polymer Thin Film Adhesion Energy on Cohesive Interactions between Chains

“…It is believed that the nanoscale interfacial layer, or the so-called “interphase” in nanocomposites, exhibits conformational and dynamical differences when compared to the bulk properties of the polymer. The stark differences observed for interphase regions are often attributed to local variations in the segmental mobility and structural relaxation of polymer chains. − Such changes are caused by the surface potential of the substrate, and the extent of the ability of the surface potential to perturb the film structure in return governs its adhesion mechanism. Unlike single chain adsorption onto surfaces, the adhesive interactions within the substrate–film interface must depend on the cohesive interactions and steric hindrances between chains.…”

Achieving directional migration of hindered phenols in polymer‐based damping hybrid via the construction of alternating layers

“…Therefore, it is widely used to explore H-bond systems. [16][17][18][19][20][21][22][23] For example, Qiao et al adopted MD simulation in hindered phenol/nitrile rubber hybrids for the first time and proposed that the damping performance was determined by the number of intermolecular H-bonds, the binding energy and the fractional free volume (FFV). The extreme value of the above three factors results in the maximum value of dynamic loss factor of the hybrids.…”