Towards understanding and directing the nitration of cellulose

Nitrocellulose is industrially produced from cellulose by treatment with nitric and sulfuric acid. While sulfuric acid is known to catalyse the hydrolysis of cellulose, its effect on nitrated cellulose has not been reported before. Herein we show by gel permeation chromatography that hydrolysis of nitrocellulose derived from cotton linters over a one-week timescale reduces the length of the polymer chains via a two-stage reaction process similar to that observed for cellulose. Powder X-ray diffraction patterns and scanning electron microscopy images of nitrated cellulose samples originating from plant and bacterial sources are compared with highly processed nitrocellulose membranes and show a variation in morphology and an enhancement of sample crystallinity. This highlights a selective mechanism where the amorphous domains are preferentially hydrolysed over the crystalline domains, which is also common behaviour with cellulose. Overall, this work shows that the timescale for nitration exerts control over the resulting product crystallinity, morphology and polymer chain length.

Graphical abstract