Glycidyl methyl ether: A safer alternative to ethylene oxide for designing ethoxy-free non-ionic surfactants

Ethoxylated surfactants have recently raised alarm because small amounts of dioxane, a Substance of Very High Concern (SVHC), are formed during their synthesis and degradation, with some of it ending up as traces in drinking water. This awareness has prompted a quest for alternative non-ionic surfactants free of ethoxylates yet offering a tuneable molecular structure and amphiphilic behaviour akin to polyethoxylated alcohols, CiEj. In this perspective, we performed oligomerization of Glycidyl Methyl Ether (GME) on fatty alcohols to yield branched isomers of CiEj surfactants. The amphiphilic properties of the resulting well-defined ethoxy-free surfactants were systematically compared to their polyethylene glycol counterparts. The introduction of branching in the polar head led to decreased hydrophilicity, as quantified by PIT-slope measurements. Furthermore, these branched surfactants exhibited cloud points with a reduced dependence on the oligomerization degree and lower Critical Micelle Concentrations (CMC). Consequently, these findings position them as promising alternatives to ethoxylated non-ionic surfactants. Finally, the COSMO-RS theory was strategically applied for the first time to rigorously rationalize the amphiphilic properties exhibited by these novel surfactants by precisely quantifying hydrophilic-lipophilic tendencies.