There are several factors determining structure of the polymer layertethered to a flat surface. One is anchor distance, or distribution of tethering sites on the surface and another is polymer molecular weight. There is a direct dependence of polymer conformation on grafting density.D = Distance between attachment points and RF = Flory radius = aNν
(RF = Flory radius, a = monomer dimension, N = degree of polymerization, ν = Flory exponent, n = 0.6 (PEO in good solvent)
Four different topologies have been described depending on relationship between density of grafting sites and Flory radius.(1)
(1) Unsworth, L. D.; Tun, Z.; Sheardown, H.; Brash, J. L. J. Colloid Interface Sci. 2005, 281, 112-121.