INHOMOGENEOUS STRUCTURE OF COLLAPSED POLYMER BRUSHES UNDER DEFORMATION

The theory of the equilibrium structure and properties of a planar bru sh under poor solvent conditions subjected to normal deformations (str etching or compression) is presented. Using a scaling type analysis, w e demonstrate that at moderate grafting densities the brush loses its lateral homogeneity and the grafted chains form aggregates (pinned mic elles) with globular cores and extended legs connecting the core with the grafting surface. These micelles are stable in a rather wide range of grafting densities provided that the chains are long and the solve nt is poor enough so that tau N-1/2 much greater than 1 Scaling relati ons as well as diagrams of states are obtained. It is shown that the n ormal deformation of the brush alters boundaries of the micelle stabil ity regime and leads to the rearrangement of the equilibrium micelle s tructure. Stretching leads to an increase in both the width of the sta bility region and the number of chains in a micelle whereas compressio n causes a decrease in these values. Different scenarios of brush defo rmation are predicted. Hysteresis effects in the processes of interact ion between brushes are discussed.