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Emulsifier design is one of the key strategies in interfacial engineering for emulsion stability. In this study, cellulose nanocrystals (CNCs) were used as an interfacial stabilizer to improve the stability of coconut oil (CO)-in-water emulsions. A Pickering emulsion consisting of CO and water was optimized based on four parameters using the response surface methodology and the central composite design. The droplet coverage remained stable during the crystallization of the oil phase when the temperature was reduced below the melting temperature of CO. Fluorescent-labeled CNCs were used to monitor the partitioning of CNC at the O/W interface during the crystallization of CO. The Generation 6 polyamidoamine (G6 PAMAM) dendrimer covalently grafted on the surface of CNC was used as an intrinsic fluorescent dye. Since it displayed similar properties as the emulsifier, it could be used to monitor the CNC coverage on the oil droplets at various temperatures. The fluorescence micrographs showed that the emission of PAMAM CNCs at the O/W interface remained on both the liquid and solid CO droplets, confirming that oil crystallization did not affect the fluorescent CNC coverage on the oil droplets.

Pickering emulsion stabilized by cellulose nanocrystals (CNCs) during the phase transition of the dispersed oil is poorly understood. We investigated the capability of CNC in stabilizing Pickering emulsions during the temperature-induced phase transition. Paraffin wax emulsions stabilized by sodium dodecyl sulfate (SDS) were less stable than CNC stabilized emulsions. The relationship between droplet size and emulsifier content was examined, and a new model describing this relationship is proposed. The droplet size of CNC-based systems was not affected by temperature variation, even at low CNC concentrations. The minimum CNC content required to stabilize the paraffin wax emulsion was lower than SDS. DSC results indicated that higher droplet surface coverage with emulsifiers enhanced the deformation resistance of the crystallized droplets, which enhanced the emulsion stability. Temperature sweep viscosity measurements showed that the stability of CNC-based systems was not significantly impacted by the phase transition of the paraffin wax. Rheological amplitude sweep analysis indicated that emulsions above the melting point of paraffin wax were more stable at all strain levels. However, the SDS-based systems displayed substantial heterogeneity after the liquid-solid transition. Frequency sweep tests revealed that CNC-stabilized emulsions were more stable than SDS-stabilized emulsions.

There is a growing interest in the synthesis of electrically conductive cellulose nanocrystal (CNC) for advanced applications, such as supercapacitor, batteries, sensor, and printed electronics. CNC is recognized as an attractive template for the fabrication of functional nanomaterials. Since CNC possesses many attractive properties, it is a sustainable template to prepare conductive nanomaterials, by either coating it with a conductive material or transforming it into carbon nanorods. This review summarizes the utilization of a sustainable and low-cost CNC to produce conductive nanocomposites via an environmentally friendly process. Electroconductive CNCs with enhanced electrical properties, lower electrical percolation threshold, and better mechanical properties can be produced and are attractive systems for many new applications.