Cellulose nanocrystals (CNCs) are rod shaped nanoparticles extracted from natural cellulose sources through a hydrolysis procedure which most commonly uses sulfuric acid. While other acids have been used for hydrolysis, they have rarely been optimized. CNCs hydrolysed with phosphoric acid have been demonstrated to have increased thermal stability [Camarero Espinosa et al. Biomacromolecules, 2013, 14, 1223]; however, we have found that the nanoparticles produced following this protocol are difficult to handle because they remain “hinged” together and have limited colloidal stability due to very few surface grafted charge groups. A design of experiments statistical analysis was performed to optimize CNCs produced by phosphoric acid hydrolysis, in terms of their thermal and colloidal stability. Specifically, acid concentration, temperature and reaction time were varied and the effects of these parameters on CNC morphology and surface chemistry were studied. It was found that the hydrolysis conditions have a significant effect on several CNC properties and the phosphoric acid hydrolyzed CNCs were compared to CNCs produced with sulfuric acid only, as well as acid blends.  All CNCs produced were thermally treated in various environments, including at high pressure, and fully characterized following treatment to elucidate the effect of surface grafted groups (and their chemical stability), degree of crystallinity, and cellulose degree of polymerization on thermal and colloidal properties. This is the first step towards a better mechanistic understanding of CNC thermal stability which ultimately will allow for the production of CNCs suitable for high temperature/pressure applications such as oil & gas drilling and completion fluids.<br/>

Optimizing both thermal and colloidal stability of cellulose nanocrystal through acid hydrolysis

253rd National Meeting (2017)

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