Thermal properties of lauric- and stearic acid intercalated layered double hydroxides

Abstract

A commercial layered double hydroxide (LDH) with nominal composition [Mg0.689A10.311(OH)2](CO3)0.156.zH2O was intercalated with lauric and stearic acid using a surfactant-assisted method. X-ray diffraction, thermal analysis and infrared spectroscopy confirmed that bilayer-intercalated compounds were formed and that the surfactant (sodium dodecyl sulfate) was not co-intercalated. These compounds shows interesting thermal behavior with two phase transformations observed at elevated temperatures. At temperatures that are significantly higher than the melting points of the corresponding free acids, the alkyl chains assume a disordered liquid-like state within the clay galleries. However, at even higher temperatures the materials become completely amorphous like true melts.