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This content will become publicly available on August 27, 2026

Title: Effects of additives on the rheology and phase behavior of lamellar-structured concentrated surfactant solutions
Structure-property-processing relationships for model lamellar structured 70 wt.% SLEnS solutions were developed with a combination of rheometry, cross-polarized optical microscopy, calorimetry, small angle X-ray scattering, and rheo-ultrasonic speckle velocimetry. Additives were utilized to maintain high surfactant activity, reduce bulk viscosity and simplify processing. While the bulk flow behavior of neat SLEnS solutions was similar, the effect of some additives was sensitive to the degree of ethoxylation. Linear-chain alcohols (C2-C5) partitioned into inter-bilayer water layers, dehydrating surfactant headgroups and inducing lamellar-to-micellar transitions. Short-chain polyols formed higher-viscosity hexagonal and mixed phases at room temperature through hydrogen bonding with surfactant headgroups. Heating beyond the upper temperature limit weakened these interactions, resulting in low-viscosity solutions. Within the lamellar phase, common salt promoted shear-induced crystallization above the equilibrium temperature range. Propylene glycol suppressed shear-induced crystallization and promoted wall-slip under shear, forming lubrication layers near the wall. These strategies offer practical levers to tune rheology and microstructure of concentrated surfactant systems, with the datasets developed providing a foundation for future modeling. Outcomes from this study inform the sustainable design and efficient processing of concentrated surfactant-based products.  more » « less
Award ID(s):
2112956
PAR ID:
10647590
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  
Publisher / Repository:
Royal Society of Chemistry
Date Published:
Journal Name:
Soft Matter
Volume:
21
Issue:
34
ISSN:
1744-683X
Page Range / eLocation ID:
6735 to 6750
Subject(s) / Keyword(s):
Concentrated surfactant solutions, ternary systems, lamellar-to-micellar transitions, shear-induced crystallization, wall slip.
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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