Cellulose nanofiber-derived efficient stabilizer for oil-in-water high-internal-phase emulsion

Stabilization of emulsion using plant-derived nanomaterial has been of great research interest. In this regard, cellulose nanofibers (CNF) showed good potential in conventional emulsion system. Thus, it creates the scope to develop an efficient CNF-based stabilizer for high internal phase emulsion (HIPE) using a convenient process. Herein, we prepared oil-in-water (o/w) HIPEs or emulsion gels using amphiphile-grafted CNFs termed as cellulosic gelators (CLGs). The CLGs were obtained by grafting a poly(ethylene glycol)-based amphiphile (PGLE) onto CNFs by one-step etherification reaction at different degree of PGLE substitution (DS). The HIPEs remained stable at very high oil volume (upto 96.3%) and they were characterized by optical and electron microscopy, rheology and differential scanning calorimetry. The efficacy of stabilization and oil-droplet sizes were highly dependent to the DS, concentration of CLG, and the volume of aqueous phase. The beneficial effect of CNF in CLGs was observed from the higher thermal stability (control, 31.4 °C; CLG, 57.0 °C) and improved viscoelasticity (critical strain γc: control, 0.3%; CLG, 1.0%). This approach will pave the way to the application of CNFs in producing commercial HIPEs to be used in food, cosmetics and pharmaceuticals.