The relation between chemical potential and surface coverage of PNIPAM brushes in pure water, 0.25 M NaI solution, 0.25 M NaBr solution, and 0.25 M NaCl solution at (a) T = 25 °C and (b) T = 35 °C. The molecular weight of the polymer chain is M_w = 22500 g·mol⁻¹, and the surface coverage is σ = 0.5 nm⁻².