Micellization behavior of anionic gemini surfactants-templated manufacture of cerium oxide nanoparticles

A series of anionic gemini surfactants (GS) were synthesized from the reactant of N, N-dimethylaminoethanol (DMEA) with dicarboxylic acid diester (DADE), after the DADE was synthesized from pyromellitic dianhydride (PMDA) and fatty alcohol. Through rational design, benzene ring was introduced into the molecular structure to work as spacer group; carboxylic acid ammonium salt with hydroxyl as functional hydrophilic head group, and double-alkyl chain performed as hydrophobic tail chains. Then, surface active properties and micellization behavior were investigated respectively. It is found that these novel molecular structure dramatically improved the surface active properties, including critical micelle concentration (CMC: 10⁻³mol/L), surface tension (γ_min: 26.5 mN/m), conductivity and absorption at interface. Moreover, GS were able to form intermolecular hydrogen bonds, which, together with rigid spacer group, greatly affected the micellization behavior in bulk solution. More importantly, the self-assembly of aggregation with different morphologies can be controlled via adjustment to solution concentration or tail chain length. Finally, GS were applied as soft templates for the shape controllable synthesis of cerium oxide (CeO₂) nanoparticles, and CeO₂ nanoparticles in diverse shapes were eventually obtained and verified, such as dorayaki shape (double-pancake shape), rod-cluster shape, lamellar shape, butterfly shape and dendrite shape.

Anionic gemini surfactants were reasonably designed and developed. And the aggregation morphology can be adjusted via changing tail chain length and concentration, which is suitable for shape controllable synthesis of CeO₂ nanoparticles.