Height Switching in Mixed Polymer Brushes with Polymers of Different Stiffnesses

The conformational properties of mixed polymer brushes made of polymers with different stiffnesses are studied by using Monte Carlo computer simulations and the Scheutjens–Fleer self-consistent field approach. We find a height-switching phenomenon for the mixed brushes consisting of flexible and semi-flexible polymers of the same chain length. The semi-flexible polymers are located above the flexible ones at weak surface attraction, whereas the flexible polymers are located above the semi-flexible ones at strong surface attraction due to the adsorption of the semi-flexible polymers. The height-switching transition point depends on the grafting density, the rigidity of the stiff polymer, and the polymer chain length. Our results indicate that it is possible to control the surface property by mixed polymer brushes.