Methods for integrating the production of carboxylated CNCs and carboxylated CNFs from cellulose are provided. Carboxylated CNCs, carboxylated cellulosic solid residues (CSRs) in the form of cellulose fibers (CF) and/or cellulose microfibrils (CMFs), and carboxylated CNFs fabricated using the methods are also provided. The methods are based on the acid hydrolysis of a cellulosic material using weak solid organic acids to produce carboxylated CNCs and CNFs with thermal stabilities that are higher than the thermal stabilities of the cellulosic materials from which they are derived.

Hydrophobic CNCs were successfully prepared by grafting amine- and thiol terminated hydrocarbons to CNCs that have been previously coated with plant polyphenols. Hydrocarbons of various chain lengths can be used to tune the hydrophobicity of the modified CNCs. After the surface modification process, CNCs can be easily redispersed in nonpolar solvents highlighting the potential of the hydrophobic CNCs in, for example, CNC reinforced nanocomposites and non-aqueous formulations.

Hydrophobic CNCs were successfully prepared by grafting amine- and thiol terminated hydrocarbons to CNCs that have been previously coated with plant polyphenols. Hydrocarbons of various chain lengths can be used to tune the hydrophobicity of the modified CNCs. After the surface modification process, CNCs can be easily redispersed in nonpolar solvents highlighting the potential of the hydrophobic CNCs in, for example, CNC reinforced nanocomposites and non-aqueous formulations.

The invention relates to a method for modifying nanofibrillar cellulose composition, comprising—preparing fibrous dispersion of ionically charged nanofibrillar cellulose (NFC), and—applying heat treatment at a temperature of at least 90° C. to the fibrous dispersion until the viscosity of NFC starts to decrease. The viscosity of the heat-treated NFC is reversible by applying shear forces to the NFC.

The invention relates to a method for modifying nanofibrillar cellulose composition, comprising—preparing fibrous dispersion of ionically charged nanofibrillar cellulose (NFC), and—applying heat treatment at a temperature of at least 90° C. to the fibrous dispersion until the viscosity of NFC starts to decrease. The viscosity of the heat-treated NFC is reversible by applying shear forces to the NFC.

The present invention relates to a process for producing a nanocellulosic material based on the use of fractioning of cellulosic pulp stream from pre-treatment or mechanical defibrillation (partially refined/defibrillated pulp) in combination with stages of mechanical defibrillation, in which both the accept fraction and the reject fraction can be conveyed to stages of consistency adjustments so as to precede another distinct defibrillation stage. For example, if the accept is conveyed to a consistency adjustment preceding a second defibrillation stage while the reject is conveyed to the other independent stage of consistency adjustment to return to the first stage of mechanical defibrillation.

The invention relates to a method for the preparation of micro- or nano crystalline cellulosic compositions from virgin cellulose containing amorphous and crystalline cellulose phases comprising the following steps: (A) contacting virgin cellulose with a first solvent, characterized in that the first solvent is an aqueous solution comprising 40-65 wt. % ZnCl.sub.2 in water, relative to the total weight of the of ZnCl.sub.2 and water, (B) dissolving the amorphous cellulosic phase, whereby the amorphous cellulosic phase is preferentially dissolved over the crystalline cellulosic phase, (C) separating the dissolved amorphous cellulose from the crystalline cellulose and preferably step C wherein the obtained micro- or nanocellulose has XRD type I structure, which then can be contacted with a second solvent comprising between 65 and 90 wt. % ZnCl.sub.2 in water to produce delaminated cellulose having XRD type II structure. The invention also relates to micro- or nano crystalline cellulose having an XRD type I structure and nano crystalline cellulose having an XRD type II structure or mixtures thereof of high crystallinity and purity and the uses thereof.

The invention relates to a method for the preparation of micro- or nano crystalline cellulosic compositions from virgin cellulose containing amorphous and crystalline cellulose phases comprising the following steps: (A) contacting virgin cellulose with a first solvent, characterized in that the first solvent is an aqueous solution comprising 40-65 wt. % ZnCl.sub.2 in water, relative to the total weight of the of ZnCl.sub.2 and water, (B) dissolving the amorphous cellulosic phase, whereby the amorphous cellulosic phase is preferentially dissolved over the crystalline cellulosic phase, (C) separating the dissolved amorphous cellulose from the crystalline cellulose and preferably step C wherein the obtained micro- or nanocellulose has XRD type I structure, which then can be contacted with a second solvent comprising between 65 and 90 wt. % ZnCl.sub.2 in water to produce delaminated cellulose having XRD type II structure. The invention also relates to micro- or nano crystalline cellulose having an XRD type I structure and nano crystalline cellulose having an XRD type II structure or mixtures thereof of high crystallinity and purity and the uses thereof.

This invention relates generally to covalently crosslinked colloidal cellulose nanocrystals (xCNC) and methods of preparation and use thereof. The colloidal cellulose nanocrystals (CNCs) are covalently crosslinked in aqueous suspension to generate a network showing tunable physicochemical properties. The xCNC structures are tunable in terms of their physicochemical properties and arrangement within the hydrogel network. The covalent crosslinking of solitary sulfonated (—OSO.sub.3) CNCs can be accomplished without prior hydroxyl replacement or functionalization.

This invention relates generally to covalently crosslinked colloidal cellulose nanocrystals (xCNC) and methods of preparation and use thereof. The colloidal cellulose nanocrystals (CNCs) are covalently crosslinked in aqueous suspension to generate a network showing tunable physicochemical properties. The xCNC structures are tunable in terms of their physicochemical properties and arrangement within the hydrogel network. The covalent crosslinking of solitary sulfonated (—OSO.sub.3) CNCs can be accomplished without prior hydroxyl replacement or functionalization.