Modeling of Bottle-Brush Polymer Adsorption onto Mica and Silica Surfaces: Effect of Side-Chain Length

Abstract

Adsorption of a series of charged bottle-brush polymers with side chains of different length on solid surfaces is modeled using a lattice mean-field theory. The bottle-brush polymers are modeled Lis being composed of two types of main-chain segments: charged segments and uncharged segments with ill attached side chain. The composition variable X denotes the percentage of charged main-chain segments and ranges from X = 0 (uncharged bottle-brush polymer) to X = 100 (linear polyelectrolyte). Two types of surfaces are considered: mica-like and silica-like. The mica-like surface possesses a constant negative surface charge density and no nonelectrostatic affinity for either main-chain or side-chain segments, whereas the silica-like Surface has a constant negative surface potential and a positive affinity for the side chains of the bottle-brush polymers. With the mica-like Surface. ill low X the surface excess becomes smaller and at X >= 25 it becomes larger with increasing side-chain length. Hence, the value of X at which the surface excess displays a maximum increases with the side-chain length. However, with the silica-like Surface the surface excess increases with increasing side-chain length at all X < 100, and the maximum of the surface excess appears at X approximate to 10 independent of the side-chain length.