The relative solution and interfacial hydrophobicity of ethylene oxide-propylene oxide-ethylene oxide block copolymers

Abstract

By varying the ratio of the ethylene oxide (EO) to propylene oxide (PO) units in a series of poly(ethylene oxide-propylene oxide-ethylene oxide) (EPE) non-ionic copolymers we have been able to quantify the relative hydrophobic energy contribution of the EO and PO units in bulk solution and interfacial processes. These polymers are known to form aggregates in solution which consist of a hydrophobic PO core surrounded by a hydrophilic EO shell. In order to determine the hydrophobic character of the respective EPE polymers the partitioning of pyrene, a strongly hydrophobic probe, between the aqueous environment and the hydrophobic polymer environment was monitored as a function of polymer conce..