In this presentation, I will describe the latest development of producing highly crystalline, thermal stable and carboxylated cellulose nanomaterials (CNM) with or without lignin using dicarboxylic acid (DCA) especially maleic acid (MA) hydrolysis from various fiber sources including from raw biomass directly. When MA is applied to commercial pulps (either bleached or unbleached) at typical temperature of 100 <sup>o</sup>C for 60 min, it can depolymerize cellulose and substantially solubilize hemicelluloses to result in a small amount of carboxylated cellulose nanocrystals (CNCs) along with partially hydrolyzed fibers. The partially hydrolyzed fibers can be used to produce carboxylated cellulose nanofibrils (CNFs) using subsequent mechanical fibrillation with very low energy input. The amount of CNC or CNF yield along with the morphology of resultant CNFs can be tuned by adjust the hydrolysis severity. As shown in Fig. 1, one can simply eliminate the CNC separation step to feed all hydrolyzed solids into mechanical fibrillation to produce a class of morphologically tailorable and diverse carboxylated CNMs (with or without lignin depending on the feed pulp fibers). The morphology can be from CNC-like (or whiskers) to completely entangled fibril network depending on the extent of hydrolysis. The crystallinity can be affected by the extent of mechanical fibrillation. MA is also a hydrotrope that can solubilize lignin to fractionate raw biomass such as wood directly to producing carboxylated and lignin containing CNM (LCNM) at atmospheric pressure (typically at 100 <sup>o</sup>C) for 60 min. Both lignin and cellulose carboxylation makes CNMs from MA process highly dispersible in water. The MA process is scalable. I MA is a solid dicarboxylic acid with low corrosivity, which facilitate acid recovery.  MA is a US FDA approved indirect food additive, therefore, any residue left on CNM will not cause  environmental concerns.

Highly crystalline and thermal stable nanocellulose (with and without lignin) synthesized by dicarboxylic acid hydrolysis

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.