Cellulose-Based Nanofibers Processing Techniques and Methods Based on Bottom-Up Approach—A Review

Abstract

In the past decades, cellulose (one of the most important natural polymers), in the form of nanofibers, has received special attention. The nanofibrous morphology may provide exceptional properties to materials due to the high aspect ratio and dimensions in the nanometer range of the nanofibers. The first feature may lead to important consequences in mechanical behavior if there exists a particular orientation of fibers. On the other hand, nano-sizes provide a high surface-to-volume ratio, which can have important consequences on many properties, such as the wettability. There are two basic approaches for cellulose nanofibers preparation. The top-down approach implies the isolation/extraction of cellulose nanofibrils (CNFs) and nanocrystals (CNCs) from a variety of natural resources, whereby dimensions of isolates are limited by the source of cellulose and extraction procedures. The bottom-up approach can be considered in this context as the production of nanofibers using various spinning techniques, resulting in nonwoven mats or filaments. During the spinning, depending on the method and processing conditions, good control of the resulting nanofibers dimensions and, consequently, the properties of the produced materials, is possible. Pulp, cotton, and already isolated CNFs/CNCs may be used as precursors for spinning, alongside cellulose derivatives, namely esters and ethers. This review focuses on various spinning techniques to produce submicrometric fibers comprised of cellulose and cellulose derivatives. The spinning of cellulose requires the preparation of spinning solutions; therefore, an overview of various solvents is presented showing their influence on spinnability and resulting properties of nanofibers. In addition, it is shown how bottom-up spinning techniques can be used for recycling cellulose waste into new materials with added value. The application of produced cellulose fibers in various fields is also highlighted, ranging from drug delivery systems, high-strength nonwovens and filaments, filtration membranes, to biomedical scaffolds.

Impact of functional spray coatings on smoke volatile phenol compounds and Pinot noir grape growth

“…On the other hand, less guaiacol was detected in the extract solutions from CNF-CH or CNF-CDCH film, possibly due to two reasons: (1) smoke VPs were presented as bound forms although they were adsorbed and/or adsorbed, and (2) smoke VPs were blocked (neither adsorbed, nor absorbed to film). A previous study revealed that CH may interact with guaiacol smoke compounds via electrostatic interaction at low pH (Milhome et al, 2009) and hydrogen bonds (Hensley et al, 2016;Kramar & González-Benito, 2022). It was also assumed that the tight polymer-polymer network in CNF-CH and CNF-CDCH films could block guaiacol from interacting with the films since both hydroxyl and amine groups were unavailable to bind.…”

Progress and Prospects of Nanocellulose-Based Membranes for Desalination and Water Treatment

“…The CNF structure’s stability is enhanced by its crystalline character. When combined with other membrane materials having low crystallinity, CNF imparts stiffness and high strength to the nanocomposite membrane, thereby increasing water flux and antifouling in addition to the intrinsic properties [ 131 , 132 , 133 , 134 ]. In addition, CNFs are one of the best and cheapest options as they exhibit high-permeability, ultrahigh water flux, better hydrophilicity, and good salt rejection [ 135 ] when used in membranes.…”

Green Electrospinning of Biodegradable Cellulose Acetate Nanofibrous Membranes with Tunable Porosity

“…Highly porous structures with tunable pore sizes and shapes are sought-after in filtration applications. There is an increasing interest in the electrospinning of CA fibers . Ultrathin fibrous CA membranes compete with fossil-based commercial membranes in high-flux water filtration .…”

“…There is an increasing interest in the electrospinning of CA fibers. 10 Ultrathin fibrous CA membranes compete with fossil-based commercial membranes in high-flux water filtration. 11 Electrospun CA fibers were impregnated with hydroxyapatite nanoparticles as an environmentally friendly adsorption system for removing heavy metals from water.…”