Computer modeling of star polymer molecules with diblock arms

Abstract

Three different star polymer molecules in an aqueous environment were studied using molecular dynamics simulations and an explicit representation of the water solvent. The simulations for each system were performed at four different temperatures and thermally induced conformational changes were observed. Each of the three star polymers consisted of 16 diblock arms bound to a small adamantane core. The diblock arms in each case consisted of a hydrophobic region (either polylactic acid (PLA), polyvalerolactone (PVL) or polyethylene (PE)) and a PEO hydrophilic region, offering a range of conformational flexibility and different relative amounts of ester vs. aliphatic chain content. The study shows the cores to be strongly phase separated and solid-like. The ester-based systems are glassy (solid but disordered), but the polyethylene system exhibits highly ordered structure. Results suggest drug association with ester-based star polymers to be at the water-hydrophobic core interface.