Naturally derived cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are emerging nanomaterials that display high strength, high surface area, and tunable surface chemistry, allowing for controlled interactions with polymers, nanoparticles, small molecules, and biological materials. Industrial production of nanocelluloses is increasing rapidly with several companies already producing on the tons-per-day scale, intensifying the quest for viable products across many sectors. While the hydrophilicity of the nanocellulose interface has posed a challenge to the use of CNCs and CNFs as reinforcing agents in conventional plastics, it is a significant benefit for creating reinforced or structured hydrogel composites (or, when dried, aerogels) exhibiting both mechanical reinforcement and a host of other desirable properties. In this context, this Review describes the quickly growing field of hydrogels and aerogels incorporating nanocelluloses; over 200 references are summarized in comprehensive tables ...

http://pubs.acs.org/doi/pdf/10.1021/acs.chemmater.7b00531

Review of Hydrogels and Aerogels Containing Nanocellulose

With increasing environmental and ecological concerns due to the use of petroleum-based chemicals and products, the synthesis of fine chemicals and functional materials from natural resources is of great public value. Nanocellulose may prove to be one of the most promising green materials of modern times due to its intrinsic properties, renewability, and abundance. In this review, we present nanocellulose-based materials from sourcing, synthesis, and surface modification of nanocellulose, to materials formation and applications. Nanocellulose can be sourced from biomass, plants, or bacteria, relying on fairly simple, scalable, and efficient isolation techniques. Mechanical, chemical, and enzymatic treatments, or a combination of these, can be used to extract nanocellulose from natural sources. The properties of nanocellulose are dependent on the source, the isolation technique, and potential subsequent surface transformations. Nanocellulose surface modification techniques are typically used to introduce e...

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Nanocellulose, a Versatile Green Platform: From Biosources to Materials and Their Applications

Intensive exploration and research in the past few decades on polysaccharide nanocrystals, the highly crystalline nanoscale materials derived from natural resources, mainly focused originally on their use as a reinforcing nanophase in nanocomposites. However, these investigations have led to the emergence of more diverse potential applications exploiting the functionality of these nanomaterials. Based on the construction strategies of functional nanomaterials, this article critically and comprehensively reviews the emerging polysaccharide nanocrystal-based functional nanomaterials with special applications, such as biomedical materials, biomimetic optical nanomaterials, bio-inspired mechanically adaptive nanomaterials, permselective nanostructured membranes, template for synthesizing inorganic nanoparticles, polymer electrolytes, emulsion nano-stabilizer and decontamination of organic pollutants. We focus on the preparation, unique properties and performances of the different polysaccharide nanocrystal materials. At the same time, the advantages, physicochemical properties and chemical modifications of polysaccharide nanocrystals are also comparatively discussed in view of materials development. Finally, the perspective and current challenges of polysaccharide nanocrystals in future functional nanomaterials are outlined.

Preparation, properties and applications of polysaccharide nanocrystals in advanced functional nanomaterials: a review

Cellulose nanocrystals (CNCs), produced by the acid hydrolysis of wood, cotton or other cellulose-rich sources, constitute a renewable nanosized raw material with a broad range of envisaged uses: f ...

/pdf/cellulose-nanocrystal-based-materials-from-liquid-crystal-396tyw1257.pdf

Cellulose nanocrystal-based materials: from liquid crystal self-assembly and glass formation to multifunctional thin films

We demonstrate first room temperature, and ultrabright single photon emission from a color center in two-dimensional multilayer hexagonal boron nitride. Density Functional Theory calculations indicate that vacancy-related centers are a likely source of the emission.

/pdf/quantum-emission-from-hexagonal-boron-nitride-monolayers-2z38kw7vb8.pdf

Quantum emission from hexagonal boron nitride monolayers

The rheology of lyotropic cholesteric liquid crystalline phase forming double-stranded DNA (dsDNA) stabilized single-wall carbon nanotube (SWCNT) dispersions was analyzed over a wide range of SWCNT concentrations. In the semidilute regime, supernatant dispersions of dsDNA-SWCNTs showed the characteristic rheological behavior of semidilute solutions of rods predicted by the Doi-Edwards theory. These cholesterogenic liquid crystal dispersions exhibited some of the key rheological behaviors associated with lyotropic liquid crystalline polymers (LLCPs) including a non-monotonic relationship in the viscosity and moduli versus concentration curves, and the empirical Cox-Merz not being obeyed. However, the dsDNA-SWCNT viscosity versus shear rate curves exhibited an inflection point instead of the three distinct regions associated with many LLCPs and nanocylinder dispersions. This could be related to orientation defects and inherent secondary interactions between the dsDNA and the SWCNTs. Linear viscoelasticity measurements also showed similarities to other lyotropic systems.

Rheology of lyotropic cholesteric liquid crystal forming single-wall carbon nanotube dispersions stabilized by double-stranded DNA

Chirality-pure carbon nanotubes show distinct complexation with recognition DNA sequences

Tuning the optical properties of single-wall carbon nanotubes (SWCNTs) via oxygen doping has been a simple and effective approach to create fluorescent quantum emitters. We performed oxygen doping ...

Surface Coating- and Light-Controlled Oxygen Doping of Carbon Nanotubes

Stable dispersions of single-wall carbon nanotubes (SWCNTs) by biopolymers in an aqueous environment facilitate their potential biological and biomedical applications. In this report, we investigated a small library of precision synthesized glycopolymers with monosaccharide and disaccharide groups for stabilizing SWCNTs via noncovalent complexation in aqueous conditions. Among the glycopolymers tested, disaccharide lactose-containing glycopolymers demonstrate effective stabilization of SWCNTs in water, which strongly depends on carbohydrate density and polymer chain length as well. The introduction of disaccharide lactose potentially makes glycopolymers less flexible as compared to those containing monosaccharide and facilitates the wrapping conformation of polymers on the surface of SWCNTs while preserving intrinsic photoluminescence of nanotubes in the near-infrared region. This work demonstrates the synergistic effects of the identity of carbohydrate pendant groups and polymer chain length of glycopolymers on stabilizing SWCNTs in water, which has not been achieved previously.

Carbohydrate- and Chain Length-Controlled Complexation of Carbon Nanotubes by Glycopolymers.

Properties of carbon blacks and carbon black/SBR rubber composites filled by surface modified carbon blacks were examined. Although the specific surface area of carbon blacks increased after the surface modifications with heat, acid, and base, there were no obvious changes in resistivity. The composites filled by heat treated carbon blacks showed a higher tensile strength and elongation than those filled by raw blacks. The acid and base treated carbon blacks filled composites also showed higher tensile strength but similar elongation values with those filled by raw blacks. With increasing loading ratio, both tensile strength and elongation increased, and appeared a maximum value at 30-40 phr. Modulus at 300% strain remained increasing with further loading of carbon blacks. At the same loading, the heat treated black filled composites showed similar modulus values with composites filled by raw blacks but for base and acid treated black filled composites much higher values were obtained. After the surface modification, the functional groups which played an important role in reinforcement action were changed.

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Geyou Ao

Papers

Rheology of lyotropic cholesteric liquid crystal forming single-wall carbon nanotube dispersions stabilized by double-stranded DNA

Chirality-pure carbon nanotubes show distinct complexation with recognition DNA sequences

Surface Coating- and Light-Controlled Oxygen Doping of Carbon Nanotubes

Carbohydrate- and Chain Length-Controlled Complexation of Carbon Nanotubes by Glycopolymers.

Properties of Carbon Black/SBR Rubber Composites Filled by Surface Modified Carbon Blacks