Solutions of Diblock Copolymer Micelles with Bottlebrush Blocks. Scaling Model

We present a scaling theory describing equilibrium properties of starlike micelles formed by a diblock copolymer with bottlebrush (bb) blocks in solutions. In dilute and semidilute solutions, the blocks are envisioned as linear chains of impermeable superblobs with sizes D_A and D_B. Depending on the ratio of block “thicknesses”, D_A/D_B, micelles can exhibit different power law dependences on solution concentration. We demonstrate that bb branching of blocks increases the number of different regimes in the diagram of states compared with diblock copolymers with linear blocks. In particular, in concentrated solution, thickness D_A of soluble block A decreases and micelles rearrange similarly to spherical domains in melts of diblock copolymer with the concentration-dependent size of the monomer unit in the corona block. In both the semidilute and concentrated solutions, starlike micelles remain essentially impermeable and exhibit quasi-globular regimes. The theoretical predictions are contrasted to experiments.