Infrared spectroscopic investigations of the adsorption of ethylene oxide–propylene oxide copolymers from CCl4 on pyrogenic silica

Abstract

The adsorption of statistic and block copolymers of ethylene oxide (EO) and propylene oxide (PO) and of corresponding homopolymers on silica (Aerosil 200) from CCl₄ and CHCl₃ was investigated by IR spectroscopy. The adsorption isotherms were determined from the concentration difference in the solution, and the fraction of adhered segments from the IR absorption of free and hydrogen-bonded SiOH groups. Competition and displacement studies demonstrate that the EO segments are preferentially adsorbed compared with the PO segments. The fraction of adhered segments decreases with increasing amount adsorbed, molar mass, EO fraction and blocklength. The dependences are interpreted by conformational models of the block copolymers with central PO or EO blocks.