Impact of Macromolecular Architecture on Bending Rigidity of Dendronized Surfaces
Résumé
Nanomechanical properties of natural and artificial nanomembranes can be strongly affected by anchored or tethered macromolecules. The intermolecular interactions in polymeric layers give rise to so-called induced bending rigidity which complements the bare rigidity of the membrane. Using analytical mean-field theory, we explore how macromolecular architecture of tethered polymers affects the bending rigidities of the polymer-decorated membranes. The developed theory enables us to consider explicitly various polymer architectures including regular dendrons, φ-shaped, star- and comblike macromolecules as well as macrocycles. Numerical self-consistent field computations for selected (regular dendritic) topology complement the analytical theory and support its predictions. We consider both cases of (i) quenched symmetric distribution of tethered molecules on both sides of the membrane and (ii) annealing distribution in which the tethered polymers can relocate from the concave to the convex side of the membrane upon bending. We demonstrate that at a given surface coverage an increase in the degree of branching or cyclization leads to the decrease in the induced bending rigidity. Relocation of the tethered molecules from concave to convex surfaces leads to the additional decrease in polymer contribution to the membrane bending rigidity. In the latter case, a decrease in configurational entropy due to this redistributions substantially contributes to the bending rigidity