Figure 1

Ion and charge distribution and electrical potential attenuation across a surface soft layer of thickness d containing negatively charged (deprotonated) functional groups. The Donnan potential, ψ_DON, represents the potential at the rigid surface of the particle (L = −d), whereas the surface potential, ψ₀, is the potential at the soft particle surface (L = 0). The fixed charge density, ρ_fix, represents the charge density within the soft polymer layer that arises from the deprotonated functional groups of the polymer segment. The softness parameter, 1/λ, is a relative measure of the ease of water flow within the soft later. After Ohshima [22].