Highly Carboxylated Cellulose Nanofibers via Succinic Anhydride Esterification of Wheat Fibers and Facile Mechanical Disintegration

Abstract

We report herein the preparation of 4-6 nm wide carboxyl-functionalized cellulose nanofibers (CNF) via the esterification of wheat fibers with cyclic anhydrides (maleic, phtalic, and succinic) followed by an energy-efficient mechanical disintegration process. Remarkable results were achieved via succinic anhydride esterification that enabled CNF isolation by a single pass through the microfluidizer yielding a transparent and thick gel. These CNF carry the highest content of carboxyl groups ever reported for native cellulose nanofibers (3.8 mmol g). Compared to conventional carboxylated cellulose nanofibers prepared via Tempo-mediated oxidation of wheat fibers, the present esterified CNF display a higher molar-mass and a better thermal stability. Moreover, highly carboxylated CNF from succinic anhydride esterification were effectively integrated into paper filters for the removal of lead from aqueous solution and are potentially of interest as carrier of active molecules or as transparent films for packaging, biomedical or electronic applications.

Anionic wood nanofibers produced from unbleached mechanical pulp by highly efficient chemical modification

“…However, a higher temperature (90 °C), longer reaction time (5 h), and greater loading of succinic anhydride (21.5 mmol/g of pulp) were applied in the previous study. 31 Interestingly, in the current study, the carboxylic acid content of the dissolving pulp was higher than with a previously reported DES based on urea and lithium chloride, even though a succinic anhydride loading over 12 times lower was used. 15 The higher reaction efficiency might be due to the catalytic effect of imidazole.…”

“…With lignin-free bleached pulp, a carboxylic acid content of 3.8 mmol/g has been reported for succinylated fibers. 31 In the current study, lower reactivity (2.5 mmol/g) was achieved with birch pulp (which has a similar chemical composition). However, a higher temperature (90 °C), longer reaction time (5 h), and greater loading of succinic anhydride (21.5 mmol/g of pulp) were applied in the previous study.…”

“…Succinylation has previously been used as a pre-treatment to improve the nanofibrillation of bleached cellulose via anionization of its carboxylic acid groups at neutral and alkaline pH. 15,31 Succinylated GWPs were nanofibrillated with a microfluidizer to obtain AWNF1, AWNF2, and ANWF3 with carboxylic acid contents of 1.88, 2.45, and 3.34 mmol/g, respectively. After the nanofibrillation, low viscose, turbid and slightly yellowish solutions were obtained ( Figure 5).…”

High value‐added monomer chemicals and functional bio‐based materials derived from polymeric components of lignocellulose by organosolv fractionation

“…Cellulose nanofibrils are obtained by mechanical fibrillation including mechanical disintegration, homogenization, refining and ball milling, or by chemical / enzymatic hydrolysis after mechanical fibrillation. A combination of chemical and biological processes have also been reported for CNF production …”

Applications of cellulose nanomaterials in pharmaceutical science and pharmacology

“…The degree of ester substitution 2.18 is much higher than previously reported values 0.01~1. Targeting highly carboxylated CNCs, Sehaqui et al [54] studied the esterification of cellulose with succinic anhydride, following high-shear mechanical disintegration with a microfluidizer. The carboxyl groups of 3.8 mmol/g were reported as the highest value from plant cellulose.…”