Monte Carlo simulation of molecular and structural properties of mono- and bi-dispersed poly(ethylene oxide) nanofibers

Molecular and structural properties of poly(ethylene oxide), PEO, nanofibers with different diameters and molecular weights were investigated using Monte Carlo simulation of coarse-grained models on high coordination lattice. PEO nanofibers made up of mono- and bi-dispersed chains of CH₃-(OCH₂CH₂)_x-OCH₃ where x = 13 to 53, with diameter ranged from 7.4 to 16.4 times the radius of gyration of PEO chains, were analyzed. For mono-disperse chains, as a result of increasing molecular weight, the bulk density increases and the molecular size at the surface is decreased more than the nanofibers composed of shorter chain length. There is higher degree of parallel orientation of the chains and bonds at the surface and a broader region over which this bond orientation pertains. For nanofibers with mixed molecular weight, shorter chains tend to segregate at the surface and the density of short chain component is higher in this region. Compared to mono-disperse nanofibers, the properties of longer chains do not significantly change, whereas the orientation of chains and bonds for low molecular weight polymers become more anisotropic orientation in the presence of longer chains.