Self-consistent field analysis of grafted star polymers

A self-consistent mean-field treatment of star polymers grafted to an impenetrable surface is developed and used to calculate the near-surface equilibrium segment density profiles. The effects of architecture and grafting density on molecular conformation in the absence of enthalpic interactions are explored. We find that the tethering arm of a grafted star is maximally stretched at moderate grafting density, and thus the height of a layer of stars is controlled by the distribution of chains extending from the branch node into the solvent. Evidence is presented for the existence of a ''virtual surface'' at the branch node of grafted stars, above which arms stretching into the solvent behave as linear brushes independently grafted to the branch node layer. Grafted layers of stars and linear chains are contrasted by comparing the total concentration profiles and end segment distributions. Results suggest that star polymers may be superior for preparing a cell adhesion substrate characterized by high surface coverage and localization of end groups near the top of the layer.