Viscoelastic solutions formed from resveratrol-based trimeric anionic surfactants.

Abstract

Achieving high viscoelasticity in additive-free anionic surfactant systems remains a significant challenge. Herein, taking the natural product resveratrol as the starting material, a series of resveratrol-based star-type trimeric anionic surfactants (Res-trisC_<i>n</i>Na, <i>n</i> = 14, 16, 18) were designed and synthesized. These surfactants exhibit ultra-low critical micelle concentrations (CMCs < 0.01 mM), approximately three orders of magnitude lower than those of conventional single-chain counterparts. Notably, these surfactants form highly viscoelastic solutions without any additives at relatively low concentrations-a behavior rarely observed in single-component anionic surfactant systems. Res-trisC₁₆Na exhibits the best rheological performance, achieving a zero-shear viscosity of 1671.2 Pa s and a relaxation time of 41.67 s at 80 mM. Cryo-TEM and SAXS analyses confirmed the formation of flexible wormlike micelles. The remarkable viscoelasticity is attributed to the long, rigid stilbene spacer, which restricts the spatial proximity of the hydrophobic chains within individual molecules and produces a pseudo-volume, thereby favoring one-dimensional micellar growth. These findings demonstrate that long, rigid spacers are effective design elements in oligomeric surfactants forming viscoelastic solutions and provide a new route for the high-value utilization of natural products.