Density functional theory for rod-coil polymers with different size segments

Abstract

A polymer density functional theory (PDFT) for rod-coil copolymers with different size segments is proposed, in which the PDFT approach combines a modified fundamental measure theory for the excluded-volume effects, Wertheim's first-order thermodynamics perturbation theory for the chain connectivity and the mean field approximation for van der Waals attraction. First, for testing the PDFT derived, we compare the density profiles from present theory to simulation data, and find that the present theory successfully reproduces the simulation data. Therefore, we use the PDFT to further investigate the local density and solvation forces of rod-coils with different size (A(5)D(3)) and the same size (A(5)B(3)) segments. Results indicate that the excluded volume effect from the coil part determines the solvation force profiles of two rod-coil brushes at strong surface energy. In addition, owing to the vacuum effect, the weak attraction around the classical contact of the rod-coil brushes is also observed. In short, the present theory can be easily applied to the other architecture polymers containing different size segments. It is expected that the calculation results in this work could provide useful reference to select the rod-coils as stabilizer for the protection of surfaces or the colloidal stabilization.