CO2-Switchable Dispersion of a Natural Chitosan and its Application as a Responsive Pickering Emulsifier

Publication date: Available online 25 June 2018Source: Colloids and Surfaces A: Physicochemical and Engineering AspectsAuthor(s): Dongyin Ren, Shengming Xu, Dejun Sun, Qibao Wang, Zhenghe XuAbstractThe natural chitosan aggregates obtained by increasing pH are found to be responsive to CO2/N2 switching. These chitosan aggregates can be dispersed in water upon CO2 bubbling and precipitated out with N2 bubbling at room temperature. Liquid paraffin-in-oil Pickering emulsions are prepared using these aggregates as the stabilizer. These emulsions can be demulsified completely with CO2 bubbling, and the separated two phases can be re-emulsified with N2 bubbling under mechanical mixing. This CO2/N2-switched demulsification/re-emulsification cycle can be repeated several times. The CO2/N2-switched dispersion/aggregation of the chitosan aggregates leads to desorption/re-absorption of the aggregates at the oil/water interface and hence the disappearance/reconstruction of the three-dimensional network structure of the aggregates, which is responsible for the demulsification/re-emulsification. Experimental evidence including the measurement of interfacial tension, interfacial dilatational elastic modulus, and rheological properties and micrographs of formed emulsions is given to support the proposed stabilization mechanism.Graphical abstract

Source: Colloids and Surfaces A: Physicochemical and Engineering Aspects - July 11, 2018 Category: Chemistry Source Type: research