Hydrophobic modification of hemp powders for their application in the stabilization of Pickering emulsions

The high hydrophilicity of hemp powder (HP) due to the phenolic hydroxyls limits their application in the preparation of Pickering emulsions (PEs). For this purpose, this study modified the surface of HP with sodium hydroxide (NaOH) and n-butyl bromide (n-BB) to tune its wettability so that it can be used as an effective emulsifier in PEs formulations. The structure and composition of modified HP were characterized by SEM, EDX, TG, DSC,FTIR and TCA. The results indicated that the phenolic hydroxyls had been partially converted to the phenolic ethers. By systemically optimized the modifiers contents and reaction time, the HP with balanced surface amphiphilicity was obtained. Long-term stable PEs with homogeneous droplets could be successfully fabricated using modified HP. Moreover, the PEs also displayed better sun-screening performance compared with the unmodified HP aqueous solutions. This finding broadened the potential applications of HP in the coatings, cosmetic and other fields. Graphical abstract