TY - JOUR
T1 - Isotropic-nematic transition in micellized solutions
AU - McMullen, William E.
AU - Gelbart, William M.
AU - Ben-Shaul, Avinoam
PY - 1984
Y1 - 1984
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=36549099156&partnerID=8YFLogxK
U2 - 10.1063/1.448597
DO - 10.1063/1.448597
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AN - SCOPUS:36549099156
SN - 0021-9606
VL - 82
SP - 5616
EP - 5623
JO - The Journal of Chemical Physics
JF - The Journal of Chemical Physics
IS - 12
ER -