Isotropic-nematic transition in micellized solutions

William E. McMullen*, William M. Gelbart, Avinoam Ben-Shaul

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

68 Scopus citations

Abstract

We treat the isotropic-to-nematic transition in polydisperse suspensions of micellar rods. By generalizing an early theory of Onsager, we obtain a first-order transition in which the ordered rods are significantly longer than those in the (coexisting) isotropic phase. We show that this "growth" is driven by the free energy term arising from loss of orientational entropy upon alignment. For large aggregates the product ρL̄2D (where L̄ is a number-averaged length, D the diameter of the rods, and ρ the number density of aggregates) is roughly constant for each phase at coexistence. The transition value of the (nematic) order parameter (≃〈P2(cos θ)〉) first increases linearly with aggregation number s (for small rods) and approaches unity asymptotically (for large s). We compare our results to those of an earlier, monodisperse treatment of this system and interpret the nematic-induced growth in terms of coupling between rod size and alignment in micellar solutions.

Original languageEnglish
Pages (from-to)5616-5623
Number of pages8
JournalThe Journal of Chemical Physics
Volume82
Issue number12
DOIs
StatePublished - 1984

Fingerprint

Dive into the research topics of 'Isotropic-nematic transition in micellized solutions'. Together they form a unique fingerprint.

Cite this