Branching and Alignment in Reverse Worm-Like Micelles Studied with Simultaneous Dielectric Spectroscopy and RheoSANS

Published

July 14, 2018

Author(s)

John K Riley, Jeffrey J Richards, Norman J. Wagner, Paul Butler

Abstract

Micellar topology and branching play an important by poorly understood role in controlling the mechanical and flow properties of worm-like micelles (WLMs). To address the challenge of characterizing branching during flow of WLMs, we perform simultaneous dielectric spectroscopy, rheology, and small-angle neutron scattering (Dielectric RheoSANS) experiments to measure the concurrent evolution of conductivity, permittivity, stress, and segmental anisotropy of semi-dilute reverse WLMs under steady-shear flow. Reverse WLMs comprised of the double-chained phospholipid surfactant soy lecithin dispersed in an oil continuous phase with small quantities of water solubilized in the micelle core exhibit mild branching in deuterated ndecane and no branching in deuterated cyclohexane, and their electrical properties driven primarily by chain alignment, while the branched micelles undergo pronounced non-monotonic change in permittivity and conductivity consistent with breaking of branch points at low shear rates and chain alignment at high shear rates. These results provide the first direct signatures of changes in branching and connectivity during flow of WLMs.

Citation

Soft Matter

Volume

14

Issue

26

Pub Type

Journals

Download Paper

Local Download

Keywords

neutron scattering, worm-like micelles, RheoSANS, dielectric spectroscopy

Citation

, J. , , J. , , N. and Butler, P. (2018), Branching and Alignment in Reverse Worm-Like Micelles Studied with Simultaneous Dielectric Spectroscopy and RheoSANS, Soft Matter, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=925089 (Accessed April 25, 2024)