Role of Copolymer Architecture on Adsorption at the Solid/Liquid Interface

Abstract

The adsorption of monodisperse block copolymers comprising poly(ethylene oxide)−poly(butylene oxide) onto polystyrene latex from aqueous solution has been investigated by small-angle neutron scattering and photon correlation spectroscopy with particular reference to the role of molecular architecture. It appears that chain architecture is (i) a weak factor in the adsorption behavior when the hydrophobic block is located in the center of the polymer, since the triblock E 100 B 15 E 100 behaved very similarly to the cyclic c-E 200 B 15, but (ii) a significant factor when the hydrophobic block is located at the end of the copolymer chain, as shown by the more dense and thicker layer formed by E 200 B 15 compared to the triblock E 100 B 15 E 100 . The hydrodynamic thickness of the layer formed by the small diblock E 100 B 15 was approximately half that exhibited by the larger diblock E 200 B 15 . Good agreement was observed between depletion and SANS-derived adsorbed amounts. Theoretical predictions and self-consistent mean-field calculations of the adsorption also show excellent qualitative agreement with experiment.