Cellulose nanocrystals, a class of fascinating bio-based nanoscale materials, have received a tremendous amount of interest both in industry and academia owing to its unique structural features and impressive physicochemical properties such as biocompatibility, biodegradability, renewability, low density, adaptable surface chemistry, optical transparency, and improved mechanical properties. This nanomaterial is a promising candidate for applications in fields such as biomedical, pharmaceuticals, electronics, barrier films, nanocomposites, membranes, supercapacitors, etc. New resources, new extraction procedures, and new treatments are currently under development to satisfy the increasing demand of manufacturing new types of cellulose nanocrystals-based materials on an industrial scale. Therefore, this review addresses the recent progress in the production methodologies of cellulose nanocrystals, covering principal cellulose resources and the main processes used for its isolation. A critical and analytical examination of the shortcomings of various approaches employed so far is made. Additionally, structural organization of cellulose and nomenclature of cellulose nanomaterials have also been discussed for beginners in this field.

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Recent progress in cellulose nanocrystals: sources and production

Conducting polymers are extensively studied due to their outstanding properties, including tunable electrical property, optical and high mechanical properties, easy synthesis and effortless fabrication and high environmental stability over conventional inorganic materials Although conducting polymers have a lot of limitations in their pristine form, hybridization with other materials overcomes these limitations The synergetic effects of conducting polymer composites give them wide applications in electrical, electronics and optoelectronic fields An in-depth analysis of composites of conducting polymers with carbonaceous materials, metal oxides, transition metals and transition metal dichalcogenides etc is used to study them effectively Here in this review we seek to describe the transport models which help to explain the conduction mechanism, relevant synthesis approaches, and physical properties, including electrical, optical and mechanical properties Recent developments in their applications in the fields of energy storage, photocatalysis, anti-corrosion coatings, biomedical applications and sensing applications are also explained Structural properties play an important role in the performance of the composites

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Conducting polymers: a comprehensive review on recent advances in synthesis, properties and applications

A simple approach was developed to isolate cellulose nanocrystals (CNCs) with carboxylic groups from microcrystalline cellulose (MCC). The effect of reaction time on the morphology, microstructure, and thermal stability of isolated CNCs was investigated. The rod-like CNCs with size of 200–250 nm in length and about 15–20 nm in width were obtained by one-step citric/hydrochloric acid (C6H8O7/HCl) hydrolysis of MCC. The CNCs extracted at 4 h showed the highest carboxylic group content which led to a high absolute zeta potential value up to 46.63 mV. Moreover, these CNCs may be used as cationic dye adsorbent (methylene blue) and efficient flocculants with excellent coagulation–flocculation capability to kaolin suspension with a turbidity removal of 99.5%.

New Approach for Single-Step Extraction of Carboxylated Cellulose Nanocrystals for Their Use As Adsorbents and Flocculants

Recently, there has been tremendous progress in the field of nanodimensional conducting polymers with the objective of tuning the intrinsic properties of the polymer and the potential to be efficient, biocompatible, inexpensive, and solution processable. Compared with bulk conducting polymers, conducting polymer nanostructures possess a high electrical conductivity, large surface area, short path length for ion transport and superior electrochemical activity which make them suitable for energy storage and conversion applications. The current status of polymer nanostructure fabrication and characterization is reviewed in detail. The present review includes syntheses, a deeper understanding of the principles underlying the electronic behavior of size and shape tunable polymer nanostructures, characterization tools and analysis of composites. Finally, a detailed discussion of their effectiveness and perspectives in energy storage and solar light harvesting is presented. In brief, a broad overview on the synthesis and possible applications of conducting polymer nanostructures in energy domains such as fuel cells, photocatalysis, supercapacitors and rechargeable batteries is described.

Nanostructured conducting polymers for energy applications: towards a sustainable platform

The recent strategies in preparation of cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) were described. CNCs and CNFs are two types of nanocelluloses (NCs), and they possess various superior properties, such as large specific surface area, high tensile strength and stiffness, low density, and low thermal expansion coefficient. Due to various applications in biomedical engineering, food, sensor, packaging, and so on, there are many studies conducted on CNCs and CNFs. In this review, various methods of preparation of CNCs and CNFs are summarized, including mechanical, chemical, and biological methods. The methods of pretreatment of cellulose are described in view of the benefits to fibrillation.

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Recent Strategies in Preparation of Cellulose Nanocrystals and Cellulose Nanofibrils Derived from Raw Cellulose Materials

An efficient and low-cost approach to prepare spherical cellulose nanocrystals (SCNCs) is presented through chemical hydrolysis of lyocell fibers in an ammonium persulfate (APS) solution. The as-prepared cellulose nanoparticles were characterized by scanning electron microscopy, atomic force microscopy, laser light scattering particle analysis, wide angle X-ray diffraction, Fourier transform infrared spectrometry and thermal gravimetric analysis. Effects of hydrolysis conditions, such as reaction time and temperature, and APS concentration on the morphology, microstructure, and thermal stability of cellulose nanoparticles are discussed. Moreover, it is found that under mild reaction conditions, cellulose nanoparticles are spherical particles with a narrow diameter distribution, and have a cellulose II polymorphic crystalline structure with surface carboxyl groups. The optimal hydrolysis time was found to be around 16 h for hydrolysis at 80 °C with a 1 M APS aqueous solution.

Efficient extraction of carboxylated spherical cellulose nanocrystals with narrow distribution through hydrolysis of lyocell fibers by using ammonium persulfate as an oxidant

Tao Li

Papers

Efficient extraction of carboxylated spherical cellulose nanocrystals with narrow distribution through hydrolysis of lyocell fibers by using ammonium persulfate as an oxidant

Poly(aniline-co-pyrrole) on the surface of reduced graphene oxide as high-performance electrode materials for supercapacitors

Polyaniline nanostructures tuning with oxidants in interfacial polymerization system

Morphology-dependent capacitive properties of three nanostructured polyanilines through interfacial polymerization in various acidic media

One–pot synthesis and electrochemical properties of polyaniline nanofibers through simply tuning acid–base environment of reaction medium