Molecular weight-controllable regenerated cellulose nanocrystal for Pickering emulsion application

Using NaOH/urea/water system as the solvent and anhydrous ethanol as the anti-solvent，a series of regenerated cellulose nanocrystal （RCNC） with controllable molecular weights and gradually decreasing yet stabilized sizes are prepared through a multi-step precipitation method. High-performance liquid chromatography and transmission electron microscopy results reveal that the sizes of the obtained RCNC gradually decreased as their molecular weights decreased （from 36 kDa to 9 kDa）. Pickering emulsion stability tests indicate that the prepared RCNC exhibits excellent emulsifying properties. Among them，RCNC-15 with an average molecular weight of 15 kDa exhibits the best emulsifying performance，with the smallest emulsion droplet size and the optimal emulsion stability at low concentrations. Using the RCNC with the best emulsifying properties as the carrier，zinc oxide nanoparticles are grown in-situ on it to conduct emulsion-assisted photo-degradation tests of Nile red. The degradation rate reaches 99.5% within 100 min，indicating that the obtained RCNC could be served as an efficient emulsion-assisted reaction carrier.