A class of surfactants via PEG modification of the oleate moiety of lactonic sophorolipids: synthesis, characterisation and application

Abstract

There is ever increasing demand to develop surfactants based on sophorolipids because they are produced by non-pathogenic organisms, biodegradable and less toxic to humans and the environment. Herein, commercially available lactonic sophorolipid was modified via epoxidation of the fatty acid units CC and subsequent ring-opening of the oxirane with poly(ethylene glycol) of vary chain lengths to deliver a novel range of non-ionic sophorolipid-based surfactants. The methods employed for ring-opening reaction lead to a final surfactant synthesis involving heterogeneous catalysis (metal-exchanged montmorillonite), use of a benign solvent (ethyl acetate) and short reaction time (60 minutes). The resulting surfactants were structurally characterised and a prediction of their potential applications achieved using the hydrophilic-lipophilic balance (HLB) concept, foam capacity and stability of the surfactants at 0.25% surfactant solution. This new family of bio-derivable non-ionic surfactants will be useful as wetting and solubilising agents, oil-in-water emulsifiers and detergents.