Molecular Dynamics Simulations of Polymer Nanocomposites Welding: Interfacial Structure, Dynamics and Strength

Abstract

Polymer welding has received numerous scientific attention, however, the welding of polymer nanocomposites (PNCs) has not been studied yet. In this work, via coarse-grained molecular dynamics simulation, the attention on investigating the welding interfacial structure, dynamics, and strength by constructing the upper and lower layers of PNCs, by varying the polymer-nanoparticle (NP) interaction strength 𝝐 NP-p is focused. Remarkably, at low 𝝐 NP-p , the NPs gradually migrate into the top and bottom surface layer perpendicular to the z direction during the adhesion process, while they are distributed in the middle region at high 𝝐 NP-p . Meanwhile, the dimension of polymer chains is found to exhibit a remarkable anisotropy evidenced by the root-mean-square radius of gyration in the xy-(R g,xy ) and z-(R g,z ) component. The welding interdiffusion depth increases the fastest at low 𝝐 NP-p , attributed to the high mobility of polymer chains and NPs. Lastly, although the mechanical properties of PNCs at high 𝝐 NP-p is the strongest because of the presence of the NPs in the bulk region, the welding efficiency is the greatest at low 𝝐 NP-p . Generally, this work provides a fundamental understanding of the interfacial welding of PNCs, in hopes of guiding to design and fabricate excellent self-healable PNCs.

Molecular Dynamics Simulation of Polymer Nanocomposites with Supramolecular Network Constructed via Functionalized Polymer End-Grafted Nanoparticles

“…All the MD simulations were carried out using the Largescale Atomic/Molecular Massively Parallel Simulator (distributed by Sandia National Laboratories) [ 38 ]. More details of the simulation techniques can be found in our previous work [ 39 , 40 , 41 , 42 ].…”