Characterization of the micro and nanostructure of the candelilla wax organogels crystal networks

Candelilla wax (CW) organogels were produced with and without emulsifiers in high oleic safflower oil. The organogel's crystal structure was imaged at the micro and nanoscale using polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The PLM micrographs of the CW organogels displayed a large number of grainy birefringent crystals which size and proximity was below the resolution limit of this technique. The best details of the crystal network microstructure were obtained using SEM of deoiled organogels without deposition of contrast elements. Using this method, a continuous three-dimensional structure of CW branched microplatelets (2–5 μm length) was observed forming micropores where the vegetable oil was immobilized. The mechanical disruption of the organogels dispersed in cold isobutanol allowed the breakdown of the microplatelets into irregularly shaped nanoplatelets (4–40 nm length). TEM images allowed imaging the distances between planes of the lateral packing of hydrocarbon chains in the CW nanoplates. The CW nanoplatelets’ crystal domain, calculated with the Scherrer's equation, was within the range determined for triacylglycerols crystals. The emulsifiers produced a slight decrease in the observed crystal size at the microscale, while the crystal domain associated with the nanoplelets thickness increased.