Role of block size asymmetry on the adsorbed amount of polystyrene-b-poly(ethylene oxide) on mica surfaces from toluene

Abstract

The extended lenghth L of the styrene-ethylene oxide block copolymers has been measured with the surface force apparatus and shown to scale as L∼N PS N PEO 1/3 for moderately asymmetric copolymers (1<<β<<N PEO 1/2 ). Deviations are observed when the nonadsorbing block is either much larger than the anchor block or approximately the same size. A general method using IR spectroscopy was developed which can measure the quantity of adsorbed polymers on mica. The Alexander-de Gennes scaling law for the surface density, L∼N B σ 1/3 , was found to be roughly obeyed over a wide range of molecular weights and radius ratio β