[[alternative]]Monte Carlo Simulation of Polymer Brush

[[abstract]]Abstract Three dimensional Monde-Carlo simulations of flexible and semi-flexible polymer brushes at various coverage are carried out to study their equilibrium structure and attendant properties by using the bond fluctuation model. Our simulation results of long flexible polymer brushes are in general consistent with predictions of the self-consistent field theory. At low grafting densities, a parabolic brush with a depletion layer near the substrate is observed, while the depletion layer disappears and the monomer density near the substrate is enhanced due to the compression of monomers outside this region at high grafting densities. The brush height of long flexible polymers is proportional to where is the number of monomers per chain and is the grafting density. For short chains , the brush height is roughly proportional to , which indicates a nonlinear stretching energy . For semi-flexible chains, the brush height can be decomposed into a term depending on the chain stiffness and the other term independent of the stiffness. is found much smaller than . Similar results have been found for the end to end distance of the chains. Moreover, we study the isotropic-to-nematic transition of polymer brushes by varying the grafting density , chain length , and the chain stiffness. The isotropic-to-nematic transition of polymer brush is found to be a continuous phase transition from our simulation results. The angular distribution of polymer bonds has also been measured at various temperature. Finally, we discuss the effects of fluctuation of local grafting density on the monomer density distribution.