Pickering Emulsions Stabilized by an Alkyl Chain-Bridged Lignin-Based Polymer without Additives and Organic Solvents

In this article, an alkyl chain-bridged lignin polymer was prepared from our previous study. Then, an ultrafiltration method was used to classify the polymer into three fractions with a narrow molecular weight distribution. These three fractions were used to prepare novel Pickering emulsions without additives and organic solvents. The results show that the Pickering emulsion with fraction-3 of the highest molecular weight shows the best result compared with the other two fractions, and the Pickering emulsion is formed of droplets. The influence of oil-water ratios and fraction-3 dosages on the Pickering emulsions was also investigated in our study. The results show that the diameter of the droplets increases with increasing oil proportion and decreases with increasing lignin-based polymer dose. UV spectroscopy shows that the prepared Pickering emulsions have strong absorption properties from 300 to 800 nm, which will be expected to be applied in cosmetics, especially in sunscreen creams. Finally, the Pickering emulsion was also used to deliver ibuprofen, and the results showed that the embedding rate was as high as 10%. It is suggested that the Pickering emulsion stabilized by lignin-based polymers can be used for drug delivery. This will provide a potential research idea for high-value applications of lignin.