Molecular simulation of hopping mechanisms of nanoparticles in regular cross-linked polymer networks

We use coarse-grained simulations to explore the diffusion mechanism of nanoparticles with different sizes at various nanoparticle-polymer interactions in regular cross-linked polymer networks. The long time diffusivities of nanoparticles show a non-monotonic tendency at various nanoparticle-polymer interactions due to the intermittent hopping of nanoparticles through network cells. The preferred locations of small nanoparticles switch from the cell centers to the corners of cells as they interact with the network more strongly, which results in the hopping energy barrier between different cells switching from cell center localization to adsorption on networks. Steric hindrance seriously hampers large nanoparticles from hopping to neighboring network cells, and the interactions between the nanoparticle and network enhance the network deformability and also affect the hopping of nanoparticles. The multiple constraint mechanisms result in the non-monotonic diffusivities of nanoparticles with different interactions and non-Brownian motions at different time scales. Our work illustrates the hopping mechanisms of nanoparticles in polymer networks from thermodynamic and dynamic points of view. Published under an exclusive license by AIP Publishing.

Automated summary

Coarse-grained simulations were used to investigate the diffusion mechanism of nanoparticles in regular cross-linked polymer networks. The diffusivities of nanoparticles showed a non-monotonic trend at different nanoparticle-polymer interactions due to intermittent hopping. Small nanoparticles preferred to move from cell centers to corners as their interactions with the network increased, while steric hindrance limited the hopping of large nanoparticles. The interactions between nanoparticles and the network affected both network deformability and nanoparticle hopping.