Nanomaterials @ Interfaces Research Group

In spite of the wide use of alkylamine (AA) surfactants, little attention has been paid to their spontaneous reactivity in air. Exposure of AA surfactants to CO₂ results in the formation of alkylammonium-alkylcarbamate (AAAC) molecular pairs. The effect of hydrocarbon chain length on the reactivity of AAs was followed by monitoring mass gain vs time under atmospheric conditions as well as in a saturated CO₂ environment. The rates of conversion to AAAC decreased with hydrocarbon chain length. Indexed powder X-ray diffractograms and the corresponding unit cells are presented for all phases of AAs and AAACs with chain lengths of 14, 16, and 18 carbons. Temperature-resolved powder X-ray diffraction of AAACs indicated anisotropic thermal expansion occurring exclusively along the a direction of the unit cell.