Application of modified cellulose nanocrystals as nonionic surfactant

A surfactant with biodegradability and amphiphilicity was prepared from cellulose nanocrystals by grafting fatty acids. The structure of the modified cellulose nanocrystals was investigated by infrared spectroscopy, XRD, particle size detection and scanning electron microscopy. The changes in surface tension of the modified cellulose nanocrystals under different salt ion concentrations and pH were tested, and the molecular model of the modified cellulose nanocrystals was constructed. The optimum reaction conditions for the grafting of different fatty acid groups were determined by the degree of substitution. Infrared characterization and X-ray diffraction analysis showed that the reactants were successfully esterified and chemically modified. The particle detection shows that the average particle size of the modified cellulose nanocrystals is slightly increased, but it is still at the nanometer level and still has large specific surface area. The surface tension of the surfactant in the aqueous phase will decrease by changing the salt concentration and pH of the test environment, while the range is not large. Therefore, using trifluoroacetic anhydride as co-reactant, long-chain fatty acids can be grafted onto cellulose nanocrystals to form hydrophobic modified cellulose nanocrystals. The modified cellulose nanocrystals have little change in average particle size and have hydrophilic and lipophilic properties and are nonionic surfactants, which can be used as emulsifier for emulsion preparation. It is found that the modified cellulose nanocrystals have good salt resistance and acid and alkali resistance by testing the changes in surface tension under different environments.