Alkyl-β-glutaines: Glucuronolactone-derived alkyl-β-d-glucuronamidopropyl betaine surfactants.

HYPOTHESIS: Incorporation of a glucofuranose linker within alkyl amidopropyl betaine surfactants modulates interfacial, bulk self-assembly and rheological behaviour. EXPERIMENT: A series of alkyl-β-d-glucuronamidopropyl betaine surfactants were synthesised to investigate how incorporation of a glucuronolactone-derived linker influences micellar curvature, rheology, and interfacial properties. FINDINGS: Small-angle neutron scattering revealed pronounced reductions in micellar curvature relative to the structurally similar family of alkylamidopropyl betaines, where charge screening was also observed to further modulate the micellar structure of these zwitterionic sugar surfactants. Depending on alkyl chain length and ionic strength, structural transitions from ellipsoids to wormlike micelles were observed, alongside the emergence of weak and polydisperse bilayer-like assembly. Substantial increases in viscosity were observed in mixed surfactant formulations, where viscosities rivalled industry formulations of sodium laureth sulfate and cocamidopropyl betaine. This work demonstrates that the glucofuranose linker enables the fine-tuning of self-assembly, while still enabling the desirable anionic-zwitterionic chassis for many commercial applications of mixed surfactant systems.