Structure in tethered chains: Polymeric micelles and chains anchored on polystyrene latex spheres

摘要

The star models are briefly summarized and used to explain the layer thickness of the soluble block of polystyrene-poly(ethylene oxide) (PS-PEO) diblock copolymer micelles in water and cyclopentane. Both the discrete blob model (DB) and the distribution density (DD) model describe well the tethered layer of the soluble block. The structure and thickness of the adlayer formed by adsorption of the PS-PEO diblock copolymer micelles onto PS lattices is strongly dependent on the radius of the latex particle and the length of the PEO block. The star model is adequate for a latex of 32 nm radius and long PEO blocks (N = 445 and 480), but deviates for smaller PEO chains (N = 148), where the adlayer thickness is well predicted by the planar brush model. This planar brush model is still valid for a latex of 54 nm radius and the same PEO chain. For longer chains and/or larger lattices, neither model correctly predicts the adlayer thickness because of the disruption of the micelles during their adsorption process. This disruption results in the formation of loops and trains on the PS surface that make the subsequent adsorption of more micelles and the formation of a dense adlayer difficult. [References: 53]