Structuring Pickering Emulsion Interfaces with Bilayered Coacervates of Cellulose Nanofibers and Hectorite Nanoplatelets

Abstract

In this study, we present a water-in-silicone oil (W/S) Pickering emulsion system stabilized via in situ interfacial coacervation of attractive hectorite nanoplatelets (AHNPs) and bacterial cellulose nanofibrils (BCNFs). A bilayered coacervate is generated at the W/S interface by employing the controlled electrostatic interaction between the positively charged AHNPs and the negatively charged BCNFs. The W/S interface with the bilayered coacervate shows a significant increase in the interfacial modulus by 2 orders of magnitude than that with the AHNPs only. In addition, we observe that water droplets are interconnected by the BCNF bridging across the continuous phase of silicon, which is attributed to the diffusive transport phenomenon. This droplet interconnection results in the effective prevention of drop coalescence, which is confirmed via emulsion sedimentation kinetics. These results indicate that our bilayered coacervation technology has the potential of developing a promising Pickering emulsion platform that can be used in the pharmaceutical and cosmetic industries.