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).

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 nanofibrilbased 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,

A new family of materials comprised of cellulose, cellulose nanomaterials (CNMs), having properties and functionalities distinct from molecular cellulose and wood pulp, is being developed for applications that were once thought impossible for cellulosic materials. Commercialization, paralleled by research in this field, is fueled by the unique combination of characteristics, such as high on-axis stiffness, sustainability, scalability, and mechanical reinforcement of a wide variety of materials, leading to their utility across a broad spectrum of high-performance material applications. However, with this exponential growth in interest/activity, the development of measurement protocols necessary for consistent, reliable and accurate materials characterization has been outpaced. These protocols, developed in the broader research community, are critical for the advancement in understanding, process optimization, and utilization of CNMs in materials development. This review establishes detailed best practices, methods and techniques for characterizing CNM particle morphology, surface chemistry, surface charge, purity, crystallinity, rheological properties, mechanical properties, and toxicity for two distinct forms of CNMs: cellulose nanocrystals and cellulose nanofibrils.

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Polymer nanocomposites are one of the important application areas for nanotechnology. Naturally derived organic nanophase materials are of special interest in the case of polymer nanocomposites. Carboxymethyl cellulose is a polyelectrolyte derived from natural materials. It has been extensively studied as a hydrogel polymer. Methods to modify the mechanical properties of gels and films made from CMC are of interest in our lab and in the commercial marketplace. The effect of nano-sized fillers on the properties of CMC-based composites is of interest in the development of novel or improved applications for hydrogel polymers in general and CMC in particular. This project investigated cellulose nanocrystals (CNXLs) as a filler in CMC and compared the effects to microcrystalline cellulose (MCC). The composite material was composed of CMC, MCC or CNXL, with glycerin as a plasticizer. CNXL and MCC concentrations ranged from 5% to 30%. Glycerin concentrations were kept constant at 10%. CNXLs improved the strength and stiffness of the resulting composite compared to MCC. In addition, a simple heat treatment was found to render the nanocomposite water resistant.

Cellulose nanocrystals (CNXLs) have drawn attention from researchers for their remarkable reinforcing abilities and excellent mechanical properties. CNXLs typically have high aspect ratios of around 20-50 (length/width), low density of around 1.6 g/cc, high stiffness (135 to 155 GPa), and strength (estimated at 7500 MPa). Here we utilize CNXLs in a bottom-up hierarchical assembly to produce a macroscale material. Single-stranded oligonucleotides with an amino modifier were successfully grafted on CNXLs. The molecular recognition ability of the oligomeric base pairs was then utilized by duplexing complementary oligonucleotides grafted onto separate CNXL populations. The resulting hybrid nanomaterials were analyzed using dynamic light scattering, atomic force microscopy, and UV spectroscopy.