Journal of Zhejiang University SCIENCE
(ISSN 1009-3095, Monthly)

2005   Vol. 6B   No. 3   p.219-221

Effect of polyoxypropylene chain length on the critical micelle concentration of propylene oxide-ethylene oxide block copolymers

ZHANG Zhi-guo^*, YIN Hong

(Department of Chemical Engineering, Zhejiang University, Hangzhou 310027, China)
^*E-mail: zhiguozhang2004@yahoo.com.cn
Received Oct. 26, 2004; revision accepted Dec. 4, 2004

Abstract: In this work, the surface activity of block copolymer nonionic surfactants (RPE) has been determined, i.e., critical micelle concentration (CMC), surface excess concentration (Γ), surface area demand per molecule (A), surface tension at CMC (γ_CMC). A linear decrease of ln[CMC] vs number of oxypropylene units in copolymer molecule was observed. The change in the work of cohesion per oxypropylene group when passing from molecular into micellar state, calculated from the Shinoda equation, was 0.43kT for the studied compounds.

Key words: Nonionic surfactant, Propylene oxide-ethylene oxide block copolymers, Critical micelle concentration, Micellization
doi:10.1631/jzus.2005.B0219             CLC number: O647