Chitobiose as CO2-responsive bridge: constructing wormlike micelles with sodium 2-(dodecanoyloxy)ethanesulfonate.

Abstract

Stimuli-responsive wormlike micelles (WLMs) have garnered widespread attention as intelligent soft materials, but most existing CO₂-switchable WLM systems are based on synthetic or petroleum-derived components that are toxic and non-biodegradable. To address the above problem, we have constructed a fully bio-based, ultra-low-toxicity CO₂-responsive pseudo-Gemini WLM system using sodium 2-(dodecanoyloxy)ethanesulfonate (SLI) and chitobiose, a renewable disaccharide derived from chitin. After CO₂ sparging, the primary amine of chitobiose is protonated and electrostatically binds two SLI anions to form a pseudo-gemini structure, which increases the packing parameter, and thus drives the formation of long-entangled wormlike micelles; this has been verified by cryo-TEM and rheology. The system can switch between a low-viscosity Newtonian fluid (η₀ ≈ 2.5 mPa s) and a highly viscoelastic fluid (η₀ ≈ 8500 mPa s) reversibly multiple times, with a ∼3400-fold amplitude, and has good cycling stability. The system also has an import of 78% ± 5% biodegradation in 21 days (OECD 301B) and is very gentle on the skin; it significantly outperforms traditional SDS/TMPDA. The green route can provide a good platform for CO₂-switchable soft materials and will have all sorts of applications in biomedicine, food additives and personal care products.