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

RS Chen and ZY Zhang and MY Zhou and Y Han and FZ Li and J Liu and LQ Zhang, MACROMOLECULAR RAPID COMMUNICATIONS, 43, 2200221 (2022).

DOI: 10.1002/marc.202200221

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 epsilon(NP-p) is focused. Remarkably, at low epsilon(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 epsilon(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,R-xy) and z- (R-g,R-z) component. The welding interdiffusion depth increases the fastest at low epsilon(NP-p), attributed to the high mobility of polymer chains and NPs. Lastly, although the mechanical properties of PNCs at high epsilon(NP-p) is the strongest because of the presence of the NPs in the bulk region, the welding efficiency is the greatest at low epsilon(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.

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