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.

Low Molecular Mass Gelators of Organic Liquids and the Properties of Their Gels

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

Molecular Vibrations of Three Crystal Forms of Poly(vinylidene fluoride)

Theoretical evaluation of three-dimensional elastic constants of native and regenerated celluloses : role of hydrogen bonds

Structure and thermochromic solid‐state phase transition of poly (3‐alkylthiophene)

Structural changes occurring in the ferroelectric phase transition of vinylidene fluoride-trifluoroethylene (VDF-TrFE) copolymers with the various VDF molar contents have been investigated by means of X-ray diffraction and infrared spectroscopic methods. The phase transition occurs among three crystal phases of the low-temperature (regular all-trans conformation), the high-temperature (gauche conformation with a large rotational motion), and the cooled phases (disordered trans conformation). In the copolymer with low VDF molar content less than 40%, the broad transition between the cooled phase and the high-temperature phase is observed and the conformational change from trans to gauche is not so perfect. In the range of VDF 50–60%, the transition becomes more definite, and on the way of heating the low-temperature phase transforms to the cooled phase, which transfers continuously to the high-temperature phase. For copolymers of VDF 70–80%, a clear and discontinuous first order transition between...

Structural study on ferroelectric phase transition of vinylidene fluoride-trifluoroethylene copolymers (III) dependence of transitional behavior on VDF molar content

The formation of three crystalline forms of poly(vinylidene fluoride) was studied in detail by using an apparatus for heat treatments under high pressure up to 5000 atm. Form II consisting of TGTG-type molecular chains was the most stable under atmospheric pressure, and form I, composed of planar zigzag-type chains, was formed under special conditions, such as tension, high pressure, etc. Form III may be an intermediate modification between I and II. Based upon these experimental facts, as well as the potential energy calculations of the intra- and intermolecular interactions in the crystal lattices due to the van der Waals and electrostatic forces, the relation between the conditions of formation of the three forms and their structures was examined. The planar zigzag-type conformation (in forms I and III) is considered to be less stable than the TGTG type (form II) because of the steric hindrances and electrostatic dipole interactions. In spite of the difference in the intramolecular potential energy between these two molecular conformations, the stabilities of the three crystalline forms are not so very different because of the more favorable intermolecular interaction in form I.

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Masamichi Kobayashi

Papers

Molecular Vibrations of Three Crystal Forms of Poly(vinylidene fluoride)

Theoretical evaluation of three-dimensional elastic constants of native and regenerated celluloses : role of hydrogen bonds

Structure and thermochromic solid‐state phase transition of poly (3‐alkylthiophene)

Structural study on ferroelectric phase transition of vinylidene fluoride-trifluoroethylene copolymers (III) dependence of transitional behavior on VDF molar content

Molecular Conformation and Packing of Poly(vinylidene fluoride). Stability of Three Crystalline Forms and the Effect of High Pressure