Alignment of Cellulose Nanofibers: Harnessing Nanoscale Properties to Macroscale Benefits

Abstract

In nature, cellulose nanofibers form hierarchical structures across multiple length scales to achieve high-performance properties and different functionalities. Cellulose nanofibers, which are separated from plants or synthesized biologically, are being extensively investigated and processed into different materials owing to their good properties. The alignment of cellulose nanofibers is reported to significantly influence the performance of cellulose nanofiber-based materials. The alignment of cellulose nanofibers can bridge the nanoscale and macroscale, bringing enhanced nanoscale properties to high-performance macroscale materials. However, compared with extensive reviews on the alignment of cellulose nanocrystals, reviews focusing on cellulose nanofibers are seldom reported, possibly because of the challenge of aligning cellulose nanofibers. In this review, the alignment of cellulose nanofibers, including cellulose nanofibrils and bacterial cellulose, is extensively discussed from different aspects of the driving force, evaluation, strategies, properties, and applications. Future perspectives on challenges and opportunities in cellulose nanofiber alignment are also briefly highlighted.

Recent Progress in Metal‐Organic Frameworks@Cellulose Hybrids and Their Applications

“…Generally, lengths of CNFs are in the micron scale, and their widths are from tens to hundreds of nanometers. [ 107‐110 ] CNFs were first introduced by Turbak et al . [ 111‐112 ] and Herrick et al .…”

Self-assembled cellulose nanofiber–carbon nanotube nanocomposite films with anisotropic conductivity

“…There is an increasing demand for thinner, cheaper, lighter, and more eco-friendly electrically conductive films and composites 1 with anisotropic properties 2,3 for applications including optics, sensors, actuators, aerogels, mechanical reinforcement of advanced materials, and growth guiding substrates including hydrogels for biomedical applications. 2,3 There are various motivations for material alignment in these applications, such as a need for anisotropic properties in adjusting stiffness and strength of structural materials; optimizing reinforcement efficiency in fiber-reinforced composites; and mimicking the topography and architecture of native tissues in biomedical materials and applications, especially related to cell alignment in vitro. 2 Assembled oriented particles with high aspect ratio generally exhibit anisotropic physical properties.…”

“…2,3 There are various motivations for material alignment in these applications, such as a need for anisotropic properties in adjusting stiffness and strength of structural materials; optimizing reinforcement efficiency in fiber-reinforced composites; and mimicking the topography and architecture of native tissues in biomedical materials and applications, especially related to cell alignment in vitro. 2 Assembled oriented particles with high aspect ratio generally exhibit anisotropic physical properties. If the particle is also conductive, an anisotropic conductivity may result, which is potentially useful in electronic components, capacitors, sensors, electromechanical actuators, etc.…”

“…4 Cellulose nanofibers (CNF) are an excellent candidate as a primary ingredient in such composites since they provide an eco-friendly and low-cost material alternative 1 with a potential to align and offer anisotropic properties for the resulting composite material. 2 CNF-based electrically conducting materials have been produced by coating, blending or doping CNF with conductive nanoparticles such as carbon nanotubes (CNTs). CNF act as matrix and dispersant of the conductive CNT component.…”

Induction and quantification of fiber alignment in cellulose nanofibril films

“…In nature, cellulose brils are present in the outer cell wall layer of plants and are naturally aligned to create a strong durable structure (Ye et al 2020). Controlling ber alignment in engineered constructs has the ability to modulate mechanical properties which positively correlate with the degree of ber alignment (Li et al 2021). Beyond mechanical properties, cellular interactions such as cell polarity and cell elongation are directly in uenced by ber alignment of the contact surface (Kim et al 2012).…”