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Abstract: In recent years, flexible all-solid-state supercapacitors have been widely used as the energy storage devices for various smart and wearable electronic devices. However, the design and fabrication of high-performance flexible supercapacitor electrodes is still challenging since most of the active materials used for supercapacitor electrodes lack the ability to form flexible and mechanically stable structures. Recently, cellulose nanomaterials (mainly include cellulose nanocrystals and cellulose nanofibrils) have gained extensive interests due to their large specific surface areas, versatile surface chemistry, high mechanical strength, and the ability to form mechanically stable structures (e.g., films, aerogels). These days, the design of flexible supercapacitor electrodes by combining cellulose nanomaterials with different active materials gradually attracted the attention of scholars. The main objective of this review is to give an overview of recent developments in the preparation of cellulose nanomaterials based flexible all-solid-state supercapacitor electrodes. The fabrication approach, structure characterization, and electrochemical performance of the invented cellulose nanomaterials based flexible supercapacitor are elaborated. Also, the current challenges and future outlook for the design and fabrication of cellulose nanomaterials based flexible all-solid-state supercapacitor are proposed.

Recent strategies for the sustainable preparation of cellulose nanocrystals were comprehensively reviewed. Current challenges and future perspectives on this research topic were discussed as well.

Background: Bacterial cellulose (BC) and its derivatives are a rich source of renewable natural ingredients, which are of great significance for biomedical and medical applications but have not yet been fully exploited. BC is a high-purity, biocompatible, and versatile biomaterial that can be used alone or in combination with other ingredients such as polymers and nanoparticles to provide different structural organization and function. This review briefly introduces the research status of BC hydrogels, focusing on the preparation of BC-based composite hydrogels and their applications in the field of biomedicine, particularly the wound dressings, tissue engineering scaffolds, and drug delivery. Methods: By reviewing the most recent literature on this subject, we summarized recent advances in the preparation of BC-based composite hydrogels and their advances in biomedical applications, including wound dressings, tissue engineering, and drug delivery. Results: BC composite hydrogels have broadened the field of application of BC and developed a variety of BC-based biomaterials with excellent properties. BC-based hydrogels have good biocompatibility and broad application prospects in the biomedical field. Conclusion: BC-based composite hydrogels with the advantages of 3D structure, nontoxicity, high purity, and good biocompatibility, have great prospects in the development of sustainable and multifunctional biomaterials for biomedical applications.

A flexible resistive-type polyaniline-based gas sensor was fabricated by simple dip-coating of graphene combined with in situ polymerization of aniline on a flexible waste mask substrate. The prepared polypropylene/graphene/polyaniline (PP/G/PANI) hybrid sensor demonstrated a fast response (114 s) and recovery time (23 s), ppb-level detection limit (100 ppb), high response value (250% toward 50 ppm NH

Cellulose nanopaper (CNP) made of cellulose nanofibrils (CNF) has gained extensive attention in recent years for its lightweight and superior mechanical properties alongside sustainable and green attributes. The mechanical characterization studies on CNP at the moment have generally been limited to tension tests. In fact, thus far there has not been any report on crack initiation and growth behavior, especially under dynamic loading conditions. In this work, crack initiation and growth in self-assembled CNP, made from filtration of CNF suspension, are studied using a full-field optical method. Dynamic crack initiation and growth behaviors and time-resolved fracture parameters are quantified using Digital Image Correlation (DIC) technique. The challenge associated with dynamic loading of a thin strip of CNP has been overcome by an acrylic holder with a wide pre-cut slot bridged by edge-cracked CNP. The ultrahigh-speed digital photography is implemented to map in-plane deformations during pre- and post-crack initiation regimes including dynamic crack growth. Under stress wave loading conditions, macroscale crack growth occurs at surprisingly high-speed (600-700 m/s) in this microscopically fibrous material. The measured displacement fields from dynamic loading conditions are analyzed to extract stress intensity factors (SIF) and energy release rate (G) histories. The results show that the SIF at crack initiation is in the range of 6-7 MPa(m)1/2, far superior to many engineering plastics. Furthermore, the measured values increase during crack propagation under both low- and high-strain rates, demonstrating superior fracture resistance of CNP valuable for many structural applications.