Brushes of “Aggrecan-Like” Double-Comb Polymers: Analytical and Numerical Self-Consistent Field Modeling

Analytical (SS-SCF) and numerical (SF-SCF) self-consistent field (scf) modeling is applied to investigate the equilibrium structure of planar brushes formed by double-comb (DC) polymers under good solvent conditions. The DC polymer comprises two consecutive domains with different numbers, polymerization degrees, and grafting densities of side chains, resembling proteoglycan aggrecan, a major component in synovial fluids and cartilage tissue. The analytically derived dependence of the self-consistent molecular potential on structural parameters of the DC polymer is verified by systematic comparison to numerical SF-SCF data, and ranges of validity for parabolic potential approximation are specified. Based on these predictions, we examine the equilibrium structure of brushes formed by aggrecan-like DC polymers, in which shorter side chains are located in the adjacent to the grafting surface domain, while longer ones constitute the peripheral domain. We demonstrate that progressive detachment of side chains in the peripheral domain (mimicking the chondroitin sulfate-rich domain in aggrecan) has a stronger influence on brush deswelling, which may affect its tribological properties and have biologically relevant implications.