Semi-Flexible dense polymer brushes in flow - simulation & theory

The response of dense brushes of semi-flexible polymers to flow is of great interest in both technological and biological contexts. Examples include the glycocalyx on the endothelial surface layer in blood vessels [S. Weinbaum et al., Annu. Rev. Biomed. Eng. 9, 121–167, 2007] and mucus-like layers in lungs or the interior of nuclear pores.We employ smoothed dissipative particle dynamics (SDPD) [P. Espanol, M. Revenga, Phys. Rev. E 67, 026705, 2003] simulations to study semi-flexible polymer brushes for a wide range of conditions including grafting density, polymer elasticity, and shear stress due to flow. Our simulation results are in good agreement with previous studies [Y.W. Kim et al., Macromolecules 42, 3650–3655, 2009], which focused on brushes with low grafting densities. We also propose a theoretical model which describes the deformation of dense semi-flexible polymer brushes in shear flow for a wide parameter range. The model allows us to predict effective deformation (height), inner density profile and hydrodynamic penetration depth (solvent velocity profile). Therefore, it is suitable to predict the effect of grafted surfaces on the flow profile in a slit or tube