Flame-retardant, antibacterial, liquid-barrier, and wet-strength paper enabled by cellulosic fiber-derived additives

An in-situ dissolving-co-crosslinking strategy for fabricating high-strength, wet-stable, and biocompatible multiscale cellulosic paper-based plastics

Developing degradable plastics with excellent mechanical strength and wet stability from renewable and biodegradable biomass resources remains challenging. Here, we propose a simple one-step strategy for the in-situ multiscale dissolution of cellulose and crosslinking with 1,4-butanediol diglycidyl ether (BDDE) within a mixture of BDDE and AlCl3/ZnCl2 aqueous solution at room temperature. This strategy enables the synthesis of cellulosic paper-based bioplastics with high mechanical strength and wet stability from cellulose paper. In this process, conventional cellulose paper is partially dissolved, and simultaneously, BDDE forms chemical crosslinking with undissolved micro-level, nano-level cellulose fibers and dissolved cellulose macromolecules through an autocatalytic effect from AlCl3/ZnCl2 aqueous solution, resulting in multiscale physicochemical entanglements and multiple hydrogen bonds. Hence, the prepared bioplastic's dry and wet strength reached 58.2 MPa and 24.2 MPa, respectively, about 6.9 times and 71.2 times higher than untreated paper-based materials. The prepared bioplastic showed excellent wet stability, biosafety, and biodegradability. The density functional theory (DFT) simulation data indicates that Al3+, Zn2+ ions, and freely hydrated hydrogen protons are crucial to the dissolving-co-crosslinking system. This strategy involves only green and recyclable chemicals, offering a promising pathway for producing strong and biodegradable cellulosic paper-based bioplastics as an alternative to nondegradable plastics.

Insight to critical role of surface tension for cellulose-based film: A review

Cellulose-based films are increasingly popular in material science due to their abundance, biodegradability, and strong mechanical properties, making them ideal for food packaging, pharmaceuticals, and biomedical engineering applications. However, these films often experience excessive shrinkage during formation, which can reduce their effectiveness. This review focuses on the importance of surface tension in the formation and properties of cellulose films, showing how it affects film thickness, uniformity, and mechanical strength. The review explores how chemical modifications, environmental factors, and solvent choices affect surface tension and film properties. Then, it discusses various strategies to control surface tension and reduce shrinkage, such as the controlled drying conditions, plasticizers and use of surfactants. Managing the drying environment, including temperature, humidity, and method, is crucial for controlling surface tension and shrinkage. Plasticizers enhance flexibility, allowing cellulose chains to rearrange during drying, while cationic surfactants reduce shrinkage by modifying cellulose surfaces and stabilizing film structures. Future developments could include new surface modification techniques and the use of nanocellulose to further refine film characteristics. Overall, the ability to control surface tension is key to improving the performance of cellulose-based films, meeting the rising demand for sustainable materials in various industries.

Eco-friendly and flexible polysaccharide-based packaging films for fruit preservation

Food safety and wastage caused by fruit deterioration is a serious global problem. Effective packaging systems for extending the freshness period of fruit play a key role in food safety. In this work, we constructed an eco-friendly and flexible polysaccharide-based packaging film based on hydroxypropyl guar (HPG), cellulose nanocrystals (CNCs), deep eutectic solvents (DES) and anthocyanin (Anth). DES could endow polysaccharide films with multiple hydrogen bond numbers and good stability. Hydroxypropyl guar/cellulose nanocrystals/anthocyanin with 0.2 g deep eutectic solvents (HCA-DES0.2) had good tensile properties, oxygen barrier properties (3.01 cm3/m2·day·Pa), water resistance (WCA 111.97°), antibacterial (CFU ˂ 103), and transparency (55.4 %). The preservation tests of grape and blueberry showed that the shelf life of these two fruits was 12-20 days, and the polysaccharide film had great application potential in fruit preservation.

Bridging papermaking and hydrogel production: Nanoparticle-loaded cellulosic hollow fibers with pitted walls as skeleton materials for multifunctional electromagnetic hydrogels

Electromagnetic hydrogels have attracted significant attention due to their vast potential in soft robotics, biomedical engineering, and energy harvesting. To facilitate future commercialization via large-scale industrial processes, we present a facile concept that utilizes the specialized knowledge of papermaking to fabricate hydrogels with multifunctional electromagnetic properties. The principles of papermaking wet end chemistry, which involves the handling of interactions among cellulosic fibers, fines, polymeric additives, and other components in aqueous systems, serves as a key foundation for this concept. Notably, based on these principles, the versatile use of chemical additives in combination with cellulosic materials enables the tailored design of various products. Our methodology exploits the unique hierarchically pitted and hollow tube-like structures of papermaking grade cellulosic fibers with discernible pits, enabling the incorporation of magnetite nanoparticles through lumen loading. By combining microscale softwood-derived cellulosic fibers with additives, we achieve dynamic covalent interactions that transform the cellulosic fiber slurry into an impressive hydrogel. The cellulosic fibers act as a skeleton, providing structural support within the hydrogel framework and facilitating the dispersion of nanoparticles. In accordance with our concept, the typical hydrogel exhibits combined attributes, including electrical conductivity, self-healing properties, pH responsiveness, and dynamic rheologic behavior. Our approach not only yields hydrogels with interesting properties but also aligns with the forefront of advanced cellulosic material applications. These materials hold the promise in remote strain sensing devices, electromagnetic navigation systems, contactless toys, and flexible electronic devices. The concept and findings of the current work may shed light on materials innovation based on traditional pulp and paper processes. Furthermore, the facile processes involved in hydrogel formation can serve as valuable tools for chemistry and materials education, providing easy demonstrations of principles for university students at different levels.

Nacre-Inspired Aramid Nanofibers/Basalt Fibers Composite Paper with Excellent Flame Retardance and Thermal Stability by Constructing an Organic-Inorganic Fiber Alternating Layered Structure

The flame-retardant paper has gradually evolved into a necessary material in various industries as a result of the rising importance of fire safety, energy efficiency, and environmental preservation. Traditional cellulose paper requires the addition of a large amount of flame retardants to achieve flame retardancy, which poses a serious threat to mechanical quality and the environment. Therefore, there is an urgent need to develop inorganic fiber flame-retardant paper with good flexibility, high thermal stability, and inherent flame retardancy. Herein, inspired by the "brick-and-mortar" layered structure of nature nacre, we developed a layered composite paper with a unique alternating arrangement of organic-inorganic fibers by synergistically integrating environmentally sustainable basalt fiber (BF) and high-performance aramid nanofibers (ANFs) through a vacuum-assisted filtration process. The as-prepared ANFs/BF composite paper exhibited low thermal conductivity (0.024 W m-1 K-1), high tensile strength (54.22 MPa), and excellent flexibility. Thanks to its excellent thermal stability, the mechanical strength remains at a high level (92%) after heat treatment at 300 °C for 60 min. Furthermore, the peak heat release rate and smoke generation of ANFs/BF composite paper decreased by 44.6 and 95.3%, respectively. Therefore, the composite paper is promising for applications as a protective layer in flexible electronic devices, cables, and fire-retardant and high-temperature fields.

Fabrication of transparent cellulose nanofibril composite film with smooth surface and ultraviolet blocking ability using hydrophilic lignin

Ecofriendly multifunctional films with only biomass-based components have gathered significant interest from researchers as next-generation materials. Following this trend, a TEMPO-oxidized cellulose nanofibril (TOCNF) film containing hydrophilic lignin (CL) was fabricated. To produce the lignin, peracetic acid oxidation was carried out, leading to the introduction of carboxyl groups into the lignin structure. By adding hydrophilic lignin, various characteristics (e.g., surface smoothness, UV protection, antimicrobial activity, and barrier properties) of the TOCNF film were enhanced. In particular, the shrinkage of CNF was successfully prevented by the addition of CL, which is attributed to the lower surface roughness (Ra) from 18.93 nm to 4.99 nm. As a result, the smooth surface of the TOCNF/CL film was shown compared to neat TOCNF film and TOCNF/Kraft lignin composite film. In addition, the TOCNF/CL film showed a superior UV blocking ability of 99.9 % with high transparency of 78.4 %, which is higher than that of CNF-lignin composite films in other research. Also, water vapor transmission rate was reduced after adding CL to TOCNF film. Consequently, the developed TOCNF/CL film can be potentially utilized in various applications, such as food packaging.

Flame retardant cotton fabrics with anti-UV properties based on tea polyphenol-melamine-phenylphosphonic acid

A novel, high-efficiency, phosphorus-nitrogen flame retardant based on tea polyphenol-melamine-phenylphosphonic acid (named TP-MA-PPOA) for cotton fabrics was prepared successfully. TP-MA-PPOA coating gives the cotton fabrics flame retardancy and anti-UV properties. The results reveal that the TP-MA-PPOA coating enables cotton fabrics to self-extinguish, the damage length is only 7.4 cm in vertical flame test, and the limiting oxygen index increases to 28.7%. Meanwhile, Cotton/TP-MA-PPOA also performs well in cone calorimetry test, as evidenced by 88.5% reduction of peak heat release rate, and 92.9% decrease of the fire growth rate compared with that of cotton fabrics. And the risk of fire is sharply reduced. In addition, the ultraviolet protection factor value of Cotton/TP-MA-PPOA is 35.2. Encouragingly, the TP-MA-PPOA coating shows little deterioration in the handle of the cotton fabrics.