Scattering studies of the size and structure of cellulose dissolved in aqueous hydroxide base solvents

Combining NaOH with other hydroxide bases with superior dissolution properties can be a means of improving dissolution of cellulose. However, this raises questions about how the size and structure of cellulose vary when dissolved in different hydroxide bases. Here, cellulose in aqueous solutions of NaOH, Tetramethylammonium hydroxide (TMAH), Benzyltrimethylammonium hydroxide (Triton B) and previously studied equimolar solutions of NaOH/TMAH and NaOH/Triton B were investigated using small angle X-ray scattering, static and dynamic light scattering. The results show that cellulose in NaOH(aq) is largely aggregated and that the more hydrophobic TMAH and Triton are capable of molecularly dissolving cellulose into worm-like conformations, stiffer than in NaOH. The dissolution properties of mixtures are highly dependent on the compatibility of the individual bases; in line with previous observations of the properties of the solutions which now could be correlated to the structure of the cellulose on a nano- and microscale.