Molecular simulation of nanoparticles composed of mono- and bi-dispersed poly(ethylene oxide).

Monte Carlo simulation of coarse-grained poly(ethylene oxide) (PEO) models on high-coordination lattice was employed to investigate structural properties of nanoparticles composed of mono- and bi-dispersed molecular weight PEO with diameters ranging from 7.4 to 16.4 times the radius of gyration of polymers. For mono-dispersed chains, with an increasing PEO molecular weight, the bulk density increases and nanoparticle diameter is decreased. For nanoparticles with mixed molecular weights, shorter chains tend to segregate near the surface while the longer chains have more tendency to locate near the center of the particle. There is a higher degree of parallel orientation of the chains and bonds at the surface and this bond orientation pertains to a broader region. Compared to mono-dispersed nanoparticles, bond and chain orientations for both short- and long-chain components have no noticeable difference which is in contrast to the situation in polymer thin films and nanofibers where anisotropic orientation of short chain is enhanced in the presence of longer chains in mixed molecular weight systems.