Abstract
For planar brushes made of grafted polyelectrolyte stars, an analytical theory based on a stepwise approximation of the brush density profile is developed. Particular attention is paid to the effect of formation of a layered structure with the division of stars into two populations and the influence of arm charge and salt concentration on this phenomenon.
It is shown that an increase in the number of stars with an extremely stretched arm by which the star is grafted to the surface is facilitated by an increase in the grafting density, the number of arms, or the degree of ionization of the arms. In the latter case, the average brush density decreases, while in the former two cases it increases.
It is demonstrated that the theory based on the three-step approximation of the density profile describes well the results of self-consistent field modeling and the best agreement is achieved at a high degree of ionization, a large number of arms, and a high grafting density.