Core-Modified DPD Simulations of Helical Polymers on Spherical Nanoparticle Surfaces

Polymer helices exhibit a precise arrangement of monomers and functional groups along an axis, which leads to unique chemical and physical properties, with particular uses for biological and medical applications. Mixing polymers and nanoparticles (NPs) to make nanocomposites can further enhance or augment the physical properties of materials. However, to achieve improved properties from the nanoparticle component, the spatial dispersion of NPs needs to be fine-tuned. Grafting polymers to the NP surface is one method to control dispersion. The combination of nanoparticle surface curvature and the spatial confinement between adjacent chains can alter the conformation of the grafted polymers and also affect the quality of the NP dispersion. Here, we study the structure and dynamics of helical polymers grafted to a spherical NP surface using a combination of core-modified DPD simulations and proper orthogonal decomposition (POD) of the monomer motions to examine their relaxation modes. Although the relaxation modes are not affected by the helical structure of the chains, we find quantitative differences in the structure and relaxation times of the helical brush as compared to traditional polymer-grafted NPs.