Effect of chain unsaturation on the self-association of tri- and tetraethylene glycol octyl ethers obtained by butadiene telomerization

2,7-Octadienyl ethers of tri- and tetraethylene glycol (C(8:2)E(3) and C(8:2)E(4)) have been synthesized by the atom-economical butadiene telomerization of the corresponding poly(ethylene glycols). On one hand, this synthetic path is attractive because it is expeditious and environmentally benign, and on the other hand, it provides unconventional amphiphiles for which the lipophilic chains possess two double bonds. These two unsaturations increase the global hydrophilicity of the compound, which is also highlighted by the modelization of the compounds using the conductor-like screening model for real solvents (COSMO-RS). The behavior of C(8:2)E(3) and C(8:2)E(4) in binary amphiphile/water and ternary amphiphile/oil/water systems is therefore greatly modified compared to that of the conventional fully saturated homologues (C(8)E(3) and C(8)E(4)) that are easily obtained after hydrogenation. This results in a lowered efficiency of the unsaturated compounds for oil solubilization. The usual Winsor-type microemulsion systems are formed, and for the same oil, the DLS investigation of the microstructure of the Winsor I microemulsion does not highlight any difference in the self-association between the unsaturated and saturated compounds.