Polymeric brushes with density dependent excluded volume parameters

Abstract

Based on the recognition made by de Gennes that the excluded volume parameter of poly-ethylene-oxide (PEO) might depend on the local monomer density, we study the structure of PEO brushes in the limit where a local minimum is present in the free energy functional. Within the frame work of self-consistent-field theory advocated by Miller, Witten and Cates, the model predicts that a very dense state exists near the wall as the strength of the attractive interaction between the backbone and the wall is tuned. This dense state occurs through the first order phase transition. Even without an attractive interaction, for large surface coverage, we find the collapse of polymer chains near the wall