Constructing high-density crack-microstructures within MXene interlayers for ultrasensitive and superhydrophobic cellulosic fibers-based sensors.

Incorporating biopolymers into two-dimensional transition metal carbides and/or nitrides (2D MXene) has been demonstrated as an effective strategy to improve the mechanical behaviors of MXene-based composites. However, the insulate nature of biopolymers inevitably deteriorated the electrical conductivity and the sensitivity of assembled sensors. Herein, a novel cellulose nanofiber (CNF)/MXene/carbon black (CB) composite was demonstrated as the conductive layer in eco-friendly cellulose paper-based sensors by intercalating the CB into the MXene/CNF interlayer, followed by coating hydrophobic SiO2 for encapsulation. Befitting from the high-density crack-microstructures between CB and MXene, the fabricated superhydrophobic paper CB/CNF/MXene/SiO2 sensor delivered ultrahigh sensitivity of 729.52 kPa-1, low detect limit of 0.29 Pa, rapid response time of 80 ms and excellent stability over 10,000 cycles. Moreover, the fabricated sensor was capable of detecting the physiological parameter of human (e.g. huge/subtle movements) and spatial pressure distribution. Furthermore, the presence of SiO2 layer endowed the sensor with superhydrophobic performance (water contact angle ∼158.2 o) and stable electrical signals under high moisture conditions or even under water. Our work proposed a novel strategy to boost the sensitivity of MXene-based conductive layer in flexible electronic devices.

Waterproof and ultrasensitive paper-based wearable strain/pressure sensor from carbon black/multilayer graphene/carboxymethyl cellulose composite.

Huge electronic wastes motivated the flourishing of biodegradable electrically conductive cellulosic paper-based functional materials as flexible wearable devices. However, the relatively low sensitivity and unstable output in combination with poor wet strength under high moisture circumstances impeded the practical application. Herein, a superhydrophobic cellulosic paper with ultrahigh sensitivity was proposed by innovatively employing ionic sodium carboxymethyl cellulose (CMC) as bridge to reinforce the interfacial interaction between carbon black (CB) and multilayer graphene (MG) and SiO2 nanoparticles as superhydrophobic layer. The resultant paper-based (PB) sensor displayed excellent strain sensing behaviors, wide working range (-1.0 %-1.0 %), ultrahigh sensitivity (gauge factor, GF = 70.2), and satisfied durability (>10,000 cycles). Moreover, the superhydrophobic surface offered well waterproof and self-cleaning properties, even stable running data without encapsulation under extremely high moisture conditions. Impressively, when the fabricated PB sensor was applied for electronic-skin (E-skin), the signal capture of spatial strain of E-skin upon bodily motion was breezily achieved. Thus, our work not only provides a new pathway for reinforcing the interfacial interaction of electrically conductive carbonaceous materials, but also promises a category of unprecedentedly superhydrophobic cellulosic paper-based strain sensors with ultra-sensitivity in human-machine interfaces field.

Superhydrophobic modification of cellulosic paper-based materials: Fabrication, properties, and versatile applications.

Cellulose is the cheapest and mostly widespread green raw material on earth. Due to the easy and versatile developed modification of cellulose, many cellulosic paper-based sustainable materials and their multifunctional applications have attained increasing interest under the background of the implementation of the "plastic ban" policy. However, intrinsic cellulose paper is hydrophilic and non-water-proof, which highly limited its application, thus becoming a bottleneck for the development of "cellulosic paper-based plastic replacement". Unquestioningly, the superhydrophobic modification of cellulosic paper-based materials and the extension of their high value-added applications are highly desired, which is the main content of this review. More importantly, we presented the comprehensive discussion of the functionalized applications of superhydrophobic cellulosic paper-based materials ranging from conventional products to high value-added functional materials such as paper straw and paper mulch film for the first time, which have great industrialization potential and value. This review would offer the valuable guidance and insightful information for the rational construction of sustainable superhydrophobic cellulosic paper for advanced functional devices.

Balancing the decomposable behavior and wet tensile mechanical property of cellulose-based wet wipe substrates by the aqueous adhesive.

With the current global outbreak of novel coronaviruses, the fabrication of decomposable wet wipe with sufficient wet strength to meet daily use is promising but still challenging, especially when renewable cellulose was employed. In this work, a decomposable cellulose-based wet wipe substrate is demonstrated by introducing a synthetic N-vinyl pyrrolidone-glycidyl methacrylate (NVP-GMA) adhesive on the cellulose surface. Experimental results reveal that the NVP-GMA adhesive not only significantly facilitates the chemical bonding between cellulose fibers in the wet state, but also increase the surface wettability and water retention. The as-fabricated cellulose-based wet wipe substrate displays a superb water retention capacity of 1.9 times, an excellent water absorption capacity (completely wetted with 0° water contact angle), and a perfect wet tensile index of 3.32 N.m.g-1. It is far better than state-of-the-art wet toilet wipe on the market (non-woven). The prepared renewable and degradable cellulose-based substrate with excellent mechanical strength has potential application prospects in diverse commercially available products such as sanitary and medical wet wipes.

Study on the derivation of cassava residue and its application in surface sizing.

In order to maximize value and minimize waste, carboxymethyl cellulose (CMC) and carboxymethyl starch (CMS) was synthesized via solvent method using cassava residue as raw material. The alkalization time, etherification temperature, the amounts of reactants and the alkali boiling pretreatment which influence the carboxymethylation degree of cassava residue were investigated. Additionally, we studied the variation of Cobb values and ring crush index of the corrugated medium after surface sizing with the optimized carboxymethylated cassava residue. The optimum sample and starch with the mass ratio of 1:10 were mixed to prepare the sizing agent with a concentration of 6%, which was sized on the corrugated medium with a basis weight of 112 g/m2. The Cobb value and ring crush index of the sized-corrugated medium was 26.3 g/m2 and 8.1 N·m/g, which increased by 36.3% and 32.8% respectively compared with the reference one sized with pure starch solution.