We performed coarse-grained MD simulations of polymer nanocomposites with spherical nanoparticles (NPs) on the basis of the Kremer–Grest model. Cases of “aggregated” and “dispersed” NPs are compared for repulsive and attractive interactions among the NPs and the polymers. Although a clear difference in the stress–strain relations for the interactions can be seen, a small dependence of morphological changes of positions of NPs is observed for a small mesh cross-linked polymer network. It is confirmed that the attractive interaction enhances the stress values as well as the degree of NP aggregation. For large elongation ratios, the bond orientation orders to the elongation axis are increasing. For the “aggregated” NPs, this increase is significant. We also calculated two-dimensional scattering patterns of NPs during the elongations. For strain >50%, we observed a spot pattern on structure factor S(q_x,q_yz) and a two-point bar pattern on scattering intensity I(q_x,q_yz), which have been reported in the experiments. A small dependence of the two-dimensional scattering patterns on the interactions can be observed as well as that of the NP configurations.

The mechanisms underlying the influence of the surface chemistry of inorganic materials on polymer structures and fracture behaviours near adhesive interfaces are not fully understood. This study demonstrates the first clear and direct evidence that molecular surface segregation and cross-linking of epoxy resin are driven by intermolecular forces at the inorganic surfaces alone, which can be linked directly to adhesive failure mechanisms. We prepare adhesive interfaces between epoxy resin and silicon substrates with varying surface chemistries (OH and H terminations) with a smoothness below 1 nm, which have different adhesive strengths by ~13 %. The epoxy resins within sub-nanometre distance from the surfaces with different chemistries exhibit distinct amine-to-epoxy ratios, cross-linked network structures, and adhesion energies. The OH- and H-terminated interfaces exhibit cohesive failure and interfacial delamination, respectively. The substrate surface chemistry impacts the cross-linked structures of the epoxy resins within several nanometres of the interfaces and the adsorption structures of molecules at the interfaces, which result in different fracture behaviours and adhesive strengths.

Scanning electron microscopy equipped with a focused ion beam (FIB-SEM) is a promising three-dimensional (3D) imaging technique for nano- and meso-scale morphologies. In FIB-SEM, the specimen surface is stripped by an ion beam and imaged by an SEM installed orthogonally to the FIB. The lateral resolution is governed by the SEM, while the depth resolution, i.e., the FIB milling direction, is determined by the thickness of the stripped thin layer. In most cases, the lateral resolution is superior to the depth resolution; hence,asymmetric resolutionis generated in the 3D image. Here, we propose a new approach based on an image-processing or deep-learning-based method for super-resolution of 3D images with suchasymmetric resolution, so as to restore the depth resolution to achieve symmetric resolution. The deep-learning-based method learns from high-resolution sub-images obtained via SEM and recovers low-resolution sub-images parallel to the FIB milling direction. The 3D morphologies of polymeric nano-composites are used as test images, which are subjected to the deep-learning-based method as well as conventional methods. We find that the former yields superior restoration, particularly as the asymmetric resolution is increased. Our super-resolution approach for images havingasymmetric resolutionenables observation time reduction.

We investigated a fracture of polymer nanocomposites filled with spherical nanoparticles (NPs). The dependences of the fracture on the interactions between the NPs and polymers were examined by coarse-grained molecular dynamics simulations in a deformed box with a Poisson ratio of 0.4. In order to observe the creation of nanovoids, the interaction among the polymers was set to be attractive. When the NP-polymer interaction is attractive, nanovoids appear in the bulk of polymers. On the other hand, for repulsive NP-polymer interaction, nanovoids are created at the surface between the polymers and NPs. At the same time, segregation of NPs is observed. We found that these behaviors depend on crosslink densities