Polymer Brush — Alexander-de Gennes Scaling
Blob model: steric repulsion force vs surface separation
Brush height L₀ = — nm
Alexander-de Gennes blob model: grafted chains stretch into blobs of size ξ = D (grafting spacing). Brush height L₀ = N·b·(σb²)^(1/3). Compression free energy scales as F ~ (L₀/D)^(5/4) + (D/L₀)^(7/4) per unit area — purely entropic repulsion from blob confinement.