Esterification and amidation for grafting long aliphatic chains on to cellulose nanocrystals: a comparative study

Heterogeneous modification of cellulose nanocrystals (CNC) has been achieved by using esterification and amidification to attach long aliphatic chains. Long-chain aliphatic acid chlorides and amines were used as grafting reagents. Surface grafting with acyl chains was confirmed by Fourier-transform infrared spectroscopy, elemental analysis, and X-ray photoelectron spectroscopy. It was found that the degree of substitution (DS) of the surface is highly dependent on the method of modification. Irrespective of grafting approach, the modified CNC was found to be hydrophobic after modification, as attested by contact angle measurement. The main emphasis was on the correlation between DS and the extent of surface grafting.