This critical review provides a processing-structure-property perspective on recent advances in cellulose nanoparticles and composites produced from them. It summarizes cellulose nanoparticles in terms of particle morphology, crystal structure, and properties. Also described are the self-assembly and rheological properties of cellulose nanoparticle suspensions. The methodology of composite processing and resulting properties are fully covered, with an emphasis on neat and high fraction cellulose composites. Additionally, advances in predictive modeling from molecular dynamic simulations of crystalline cellulose to the continuum modeling of composites made with such particles are reviewed (392 references).

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Cellulose nanomaterials review: structure, properties and nanocomposites

Cellulose constitutes the most abundant renewable polymer resource available today. As a chemical raw material, it is generally well-known that it has been used in the form of fibers or derivatives for nearly 150 years for a wide spectrum of products and materials in daily life. What has not been known until relatively recently is that when cellulose fibers are subjected to acid hydrolysis, the fibers yield defect-free, rod-like crystalline residues. Cellulose nanocrystals (CNs) have garnered in the materials community a tremendous level of attention that does not appear to be relenting. These biopolymeric assemblies warrant such attention not only because of their unsurpassed quintessential physical and chemical properties (as will become evident in the review) but also because of their inherent renewability and sustainability in addition to their abundance. They have been the subject of a wide array of research efforts as reinforcing agents in nanocomposites due to their low cost, availability, renewability, light weight, nanoscale dimension, and unique morphology. Indeed, CNs are the fundamental constitutive polymeric motifs of macroscopic cellulosic-based fibers whose sheer volume dwarfs any known natural or synthetic biomaterial. Biopolymers such as cellulose and lignin and † North Carolina State University. ‡ Helsinki University of Technology. Dr. Youssef Habibi is a research assistant professor at the Department of Forest Biomaterials at North Carolina State University. He received his Ph.D. in 2004 in organic chemistry from Joseph Fourier University (Grenoble, France) jointly with CERMAV (Centre de Recherche sur les Macromolecules Vegetales) and Cadi Ayyad University (Marrakesh, Morocco). During his Ph.D., he worked on the structural characterization of cell wall polysaccharides and also performed surface chemical modification, mainly TEMPO-mediated oxidation, of crystalline polysaccharides, as well as their nanocrystals. Prior to joining NCSU, he worked as assistant professor at the French Engineering School of Paper, Printing and Biomaterials (PAGORA, Grenoble Institute of Technology, France) on the development of biodegradable nanocomposites based on nanocrystalline polysaccharides. He also spent two years as postdoctoral fellow at the French Institute for Agricultural Research, INRA, where he developed new nanostructured thin films based on cellulose nanowiskers. Dr. Habibi’s research interests include the sustainable production of materials from biomass, development of high performance nanocomposites from lignocellulosic materials, biomass conversion technologies, and the application of novel analytical tools in biomass research. Chem. Rev. 2010, 110, 3479–3500 3479

Cellulose nanocrystals: chemistry, self-assembly, and applications.

Cellulose fibrils with widths in the nanometer range are nature-based materials with unique and potentially useful features. Most importantly, these novel nanocelluloses open up the strongly expanding fields of sustainable materials and nanocomposites, as well as medical and life-science devices, to the natural polymer cellulose. The nanodimensions of the structural elements result in a high surface area and hence the powerful interaction of these celluloses with surrounding species, such as water, organic and polymeric compounds, nanoparticles, and living cells. This Review assembles the current knowledge on the isolation of microfibrillated cellulose from wood and its application in nanocomposites; the preparation of nanocrystalline cellulose and its use as a reinforcing agent; and the biofabrication of bacterial nanocellulose, as well as its evaluation as a biomaterial for medical implants.

Nanocelluloses: A New Family of Nature-Based Materials

Due to their abundance, high strength and stiffness, low weight and biodegradability, nano-scale cellulose fiber materials (e.g., microfibrillated cellulose and bacterial cellulose) serve as promising candidates for bio-nanocomposite production. Such new high-value materials are the subject of continuing research and are commercially interesting in terms of new products from the pulp and paper industry and the agricultural sector. Cellulose nanofibers can be extracted from various plant sources and, although the mechanical separation of plant fibers into smaller elementary constituents has typically required high energy input, chemical and/or enzymatic fiber pre-treatments have been developed to overcome this problem. A challenge associated with using nanocellulose in composites is the lack of compatibility with hydrophobic polymers and various chemical modification methods have been explored in order to address this hurdle. This review summarizes progress in nanocellulose preparation with a particular focus on microfibrillated cellulose and also discusses recent developments in bio-nanocomposite fabrication based on nanocellulose.

Microfibrillated cellulose and new nanocomposite materials: a review

This paper provides an overview of recent progress made in the area of cellulose nanofibre-based nanocomposites. An introduction into the methods used to isolate cellulose nanofibres (nanowhiskers, nanofibrils) is given, with details of their structure. Following this, the article is split into sections dealing with processing and characterisation of cellulose nanocomposites and new developments in the area, with particular emphasis on applications. The types of cellulose nanofibres covered are those extracted from plants by acid hydrolysis (nanowhiskers), mechanical treatment and those that occur naturally (tunicate nanowhiskers) or under culturing conditions (bacterial cellulose nanofibrils). Research highlighted in the article are the use of cellulose nanowhiskers for shape memory nanocomposites, analysis of the interfacial properties of cellulose nanowhisker and nanofibril-based composites using Raman spectroscopy, switchable interfaces that mimic sea cucumbers, polymerisation from the surface of cellulose nanowhiskers by atom transfer radical polymerisation and ring opening polymerisation, and methods to analyse the dispersion of nanowhiskers. The applications and new advances covered in this review are the use of cellulose nanofibres to reinforce adhesives, to make optically transparent paper for electronic displays, to create DNA-hybrid materials, to generate hierarchical composites and for use in foams, aerogels and starch nanocomposites and the use of all-cellulose nanocomposites for enhanced coupling between matrix and fibre. A comprehensive coverage of the literature is given and some suggestions on where the field is likely to advance in the future are discussed.

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Review: current international research into cellulose nanofibres and nanocomposites

Review of Recent Research into Cellulosic Whiskers, Their Properties and Their Application in Nanocomposite Field

Cellulose nanocrystals reinforced poly(oxyethylene)

The purpose of this study was to investigate a new way of processing cellulose whiskers reinforced polymer. A stable suspension of tunicin whiskers was obtained in an organic solvent (N,N-dimethylformamide) without a surfactant addition or a chemical surface modification. Both the high value of the dielectric constant of DMF and the medium wettability of tunicin whiskers were supposed to control the stability of the suspension. The nanocomposite materials were prepared by UV cross-linking using an unsaturated polyether as matrix. The resulting films were characterized by SEM, DSC, and mechanical testing in both the linear and nonlinear domains. The processing technique from a N,N-dimethylformamide suspension was found to be successful and led to materials whose properties are similar to those obtained with aqueous medium. It could be a good alternative to broaden the number of possible polymer matrices and to allow the processing of nanocomposite materials from an organic solvent solution instead of using aqueous suspensions.

Preparation of Cellulose Whiskers Reinforced Nanocomposites from an Organic Medium Suspension

Tangling Effect in Fibrillated Cellulose Reinforced Nanocomposites

Lithium-conducting nanocomposite polymer electrolytes based on high molecular weight poly(oxyethylene) (POE) were prepared from high aspect ratio cellulosic whiskers and lithium imide LiTFSI salt. The thermomechanical behavior of the resulting films was investigated by differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. The ionic conductivity and the electrochemical stability of the nanocomposite polymer electrolytes are quite consistent with the specifications of lithium batteries. The ionic mobilities were determined by pulsed magnetic field gradient NMR, and it was shown that the reinforcement does not affect the lithium transference number. High performance nanocomposite electrolytes based on tunicin whiskers were obtained. Indeed, the filler provides a high reinforcing effect, while a high level of ionic conductivity is retained with respect to unfilled polymer electrolytes.

My Ahmed Said Azizi Samir

Papers

Review of Recent Research into Cellulosic Whiskers, Their Properties and Their Application in Nanocomposite Field

Cellulose nanocrystals reinforced poly(oxyethylene)

Preparation of Cellulose Whiskers Reinforced Nanocomposites from an Organic Medium Suspension

Tangling Effect in Fibrillated Cellulose Reinforced Nanocomposites

Nanocomposite Polymer Electrolytes Based on Poly(oxyethylene) and Cellulose Nanocrystals