Fabrication, characterization, and emulsifying properties of hexadecyltrimethylammonium bromide (CTAB) complexed alginate microgel

In the current study, complexes (CAMs) of alginate microgels (AMs) and hexadecyltrimethylammonium bromide (CTAB) were prepared, and further used to stabilize O/W emulsions. Physical properties and emulsifying capacity of CAMs with different CTAB concentration were investigated, which indicated emulsifying capacity of AMs could be extensively improved by CTAB. Improved stability against centrifugation (3000 rpm), pH value (2.0-8.0), and NaCl concentration (0-200 mM) was also reported in CAMs stabilized emulsions. Interfacial adsorption and morphology observation suggested that the interfacial activities of CAMs were benefited from CTAB complexing, and an interfacial layer could be observed on the surface of the CAMs stabilized oil droplets. In this work, even a slight amount of surfactant (0.4 mM, or 0.01456 wt% CTAB) could make remarkable improvement on the emulsifying performance of alginate microgels. However, excessive CTAB would result in over aggregation of AMs, which was not conducive to the emulsifying performance of CAMs. This study proposed that the surfactant complexing was a feasible strategy to improve the emulsifying performance of polysaccharide microgels.