Anisotropic, Flexible Wood Hydrogels and Wrinkled, Electrodeposited Film Electrodes for Highly Sensitive, Wide-Range Pressure Sensing.

Biological muscles generally possess well-aligned muscle fibers and thus excellent strength and toughness. Inspired by their microstructure, tough wood hydrogels with a preserved unique alignment of cellulose fibers, mechanical anisotropy, and desirable flexibility were developed by introducing chemically and ionically cross-linked poly(acrylic acid) (PAA) into the abundant pores of delignified wood. PAA chains well infiltrated the parallelly aligned cellulose fibers of wood and formed a layer-by-layer network structure, resulting in strong, elastic tangential, and radial wood hydrogel slices. The tangential slices had a high compressive strength of 1.73 MPa and a maximum strain at fracture of 69.4%, while those of the radial slices were 0.6 MPa and 47.0%. After sandwiching the radial and tangential hydrogel slices with reduced graphene oxide (rGO) film electrodes into capacitive pressure sensors (CPSs), the tangential CPS displayed the most desired, gradient sensitivity values in the whole stress range. Additionally, the wrinkling treatment of the rGO electrode greatly improved the capacitance responsiveness toward pressure. The real-time sensing stress values of our tangential CPS during monitoring practical human activities were calculated in the range of 0.1-1.3 MPa, demonstrating the achievement of ultrafast, highly sensitive, and wide-stress-range detection for potential applications in human-machine interfaces.

Green Construction of an Oil-Water Separator at Room Temperature and Its Promotion to an Adsorption Membrane.

Underwater superoleophobic membranes as an effective means of resisting oil stains are often subjected to cumbersome modification procedures, limited stability, and difficult expansion of assembly. To develop simple, green, stable, and scalable underwater superoleophobic films, herein, cellulose-based oil-water separators with high-efficiency oil purification were constructed by using commercial carboxymethocel (CMC) as a solute and a dimethyl sulfoxide-modified ionic liquid as a solvent. Owing to the superior dissolution, regenerability, and gelation of CMC, the metal mesh and gauze can be imparted with an excellent oleophobic ability through simple dipping, spraying, and coating of the CMC solution. As a result, these modified functionalized devices exhibit a purification capacity of more than 99.5% for various oil-water mixtures. Unexpectedly, the CMC gel coating also shields the gloves from organic solvents. Significantly, when the CMC solution is applied to an adsorption membrane, it not only endows the film with excellent oil-water separation characteristics but also enhances the adsorption amount and rate of the adsorbent. Therefore, CMC-based oleophobic materials can be widely developed and applied to a variety of fields that require oleophobic properties.