Analysis of the Longitudinal Structure of a Collapsed Molecular Bottle Brush Using a Self-Consistent Field Approach

Abstract

The two-gradient self-consistent field Scheutjens-Fleer (SCF-SF) approach is employed for study of conformational transition occurring in molecular bottle brushes upon decrease in the solvent strength for grafted chains. In particular, the solvent strength was varied from theta to poor solvent conditions. It was found that at moderately poor solvent strength the bottle brush collapses, keeping cylindrically uniform shape. Further decrease in the solvent strength leads to appearance of longitudinal undulations in the collapsed cylindrical structure. This result of our SCF modeling is in agreement with earlier predictions of scaling theory concerning longitudinal instability of uniform cylindrical structure of the collapsed brush. In particular, predicted by scaling theory dependence for the period of the structure on the degree of polymerization of grafted chains (∼n 1/2) and independence of the transition temperature of the molecular weight are in good agreement with results of our SCF modeling.