Particle Localization and Hyperuniformity of Polymer-Grafted Nanoparticle Materials
Alexandros Chremos, Jack F. Douglas
The properties of materials largely reflect the degree and character of the localization of the molecules comprising them so the study and characterization of particle localization has central significance in both fundamental science and material design. Soft materials are often comprised of deformable molecules and many of the unique properties of these materials, including many biological materials, derive from the distinct nature of particle localization in this class of materials. We study localization in a material composed of model soft particles, hard nanoparticles with grafted layers of polymers, where the molecular characteristics of the grafted layers allows us to tune the softness of their interactions. In particular, we use molecular dynamics simulation to calculate the spatial and temporal correlations of a liquid composed by polymer-grafted nanoparticles (GNP). In the absence of solvent, GNPs exhibit a reversible self-assembly into dynamic polymeric GNP structures below a temperature threshold (Ta ), suggesting a liquid-gel transition. At high temperatures, GNPs interact primarily through their polymeric coronas and the GNP motion is not strongly correlated with neighboring GNPs. At temperatures below Ta , the GNPs start to associate into polymeric clusters that progressive grow upon cooling. We calculate a number of structural and dynamical properties including radial distribution function, the static structure factor, velocity autocorrelation function, and structural relaxation times. Overall, we find a significant suppression of density fluctuations in solvent-free GNPs at long length scales. These findings suggest that solvent-free GNPs show great promise as for the practical fabrication of hyperuniform materials.
and Douglas, J.
Particle Localization and Hyperuniformity of Polymer-Grafted Nanoparticle Materials, Annalen Der Physik, [online], https://doi.org/10.1002/andp.201600342
(Accessed March 2, 2024)