SELF-CONSISTENT BROWNIAN DYNAMICS SIMULATION OF POLYMER BRUSHES UNDERSHEAR

A novel Brownian dynamics method has been developed to simulate the pr operties of polymer brushes under shear. Simulations of 100 chains wit h a chain length of 100 segments have been carried out for a range of shear rates. Compared to previous methods there is a substantial savin g in computational time as the self-consistent molecular field method has been chosen to calculate the volume interactions between polymer s egments. An important criterion for observing significant deformations of the brush is that the chains must be stretched to beyond the Gauss ian threshold. Density profiles and end segment distribution functions for the grafted chains have been determined and show a collapse of th e brush under shear in a way similar to that in which a brush contract s in a poor solvent. In particular, the free ends of the chains become concentrated in a narrow region at the periphery of the brush. The nu mber of chains that are affected by shear has also been calculated and shows that there is a progressive transmission of shear into the brus h.