Hydrothermal Gelation of Pure Cellulose Nanofiber Dispersions

Abstract

Gelation of cellulose nanofibers (CNFs) through conventional crosslinking or reprecipitation requires the use of additives. Here, for the first time, the gelation of pure CNF dispersions has been achieved solely by mechanical disintegration and a hydrothermal process without chemical modification. Different concentrations of cellulose powder were dispersed in water, following which these CNF dispersions were subjected to hydrothermal treatment at 160 °C for different lengths of times in a sealed reactor. Self-sustaining hydrogels with no discoloration were obtained. The chemical properties and crystal structures of the CNFs were essentially unchanged following hydrothermal treatment. Although the molecular mass of the cellulose was slightly lower after hydrothermal treatment, the polymer density of the cellulose at the same hydrodynamic radius was unchanged after hydrothermal treatment. Hence, chemically crosslinked

Regenerated Cellulose Microgel: A Promising Reinforcing Agent and Gelator for Soft Matter

“…One dimensional (1D) cellulose materials, such as cellulose nanofibers − (CNFs), cellulose nanocrystals, , and microfibrillated cellulose (MFC), have attracted enormous attention to be used as biobased reinforcing agents for hydrogels due to their hydrophilicity, scale-effect, and high aspect ratio. At low concentrations in the hybrid hydrogel, 1D cellulose materials act as energy absorbers similar to most nanoparticles. , While, in the hybrid hydrogel, 1D cellulose materials with a concentration higher than percolation concentration could act as a microscopic network which both supports the whole polymer matrix and absorb energy. , It should be noted that, differing from the synthetic polymer fiber, 1D cellulose materials are stiff and could only adhere or attach to the polymer matrix by a covalent or a noncovalent bond with spontaneous movement under deformation.…”

Eco-friendly Carboxymethyl Cellulose Nanofiber Hydrogels Prepared via Freeze Cross-Linking and Their Applications

“…Cellulose nanofibers (CNFs) and their applications have attracted increasing interest since the development of their manufacturing methods. − Water-dispersible nanofibers are approximately 10 nm in diameter, 0.5–2 μm wide, and consist of many hydrogen-bonded cellulose molecules. , CNFs are nontoxic, flexible, and have a large surface area; therefore, they are promising raw materials particularly for medical and environmental applications, − with the water dispersibility of CNFs substantially contributing to the effective use of cellulose, which is the most abundant natural polymer extracted from wood. , Several CNF hydrogels have been developed − that were obtained by adding an acidic solution or an aqueous metal salt solution to form hydrogen bonds or ionic interactions. Presumably, because there are high-density hydrogen-bonded clusters in CNFs that contribute to the efficient formation of cross-linked networks, it is interesting that the concentration of CNFs required for gelation was lower than that for cellulose-derivative polymers with a similar composition to CNFs .…”

Preparation of Self-Sustaining Hydrogels by Hydrothermal Gelation of Biomass-Derived Nanofibers

“…(Color online) Illustrations of the wet pulverization and hydrothermal gelation processes used to form cellulose nanofiber (CNF) hydrogels. Reprinted with permission from Ref [7]…”

“…(A) Transmittance at l＝600 nm and (B) number average CNF width of the CNF dispersion and hydrogel samples (1 wt, 50 passes) as a function of heating time. The CNF dispersion has a heating time of 0.Reprinted with permission from Ref [7]…”

“…(B) Relationship between the elution volume and elution pattern with respective molecular mass plots of CNF and hydrogel solutions in LiCl/DMAc. Reprinted with permission from Ref [7]…”