Asymmetric ionic bond shielding encountering with carboxylate capturing metal ions for enhancing the flame retardant durability of regenerated cellulose fibers.

Enhancing the flame retardancy and durability of cellulose fibers, particularly environmentally friendly regenerated cellulose fibers types like Lyocell fibers, is essential for advancing their broader application. This study introduced a novel approach to address this challenge. Cationic-modified Lyocell fibers (Lyocell@CAT) were prepared by introducing quaternary ammonium structures into the molecular chain of Lyocell fibers. Simultaneously, a flame retardant, APA, containing -COO-NH4+ and -P=O(O-NH4+)2 groups was synthesized. APA was then covalently bonded to Lyocell@CAT to prepare Lyocell@CAT@APA. Even after undergoing 30 laundering cycles (LCs), Lyocell@CAT@APA maintained a LOI value of 37.2 %, exhibiting outstanding flame retardant durability. The quaternary ammonium structure within Lyocell@CAT@APA formed asymmetric ionic bonds with the phosphate and carboxylate groups in APA, effectively shielding the binding of Na+ ions with phosphate groups during laundering, thereby enhancing the durability. Additionally, the consumption of Na+ ions by carboxylate groups further prevented their binding to phosphate groups, which contributed to enhance the durability properties. Flame retardant mechanism analysis revealed that both gas and condensed phase synergistically endowed excellent flame retardancy to Lyocell fibers. Overall, this innovative strategy presented a promising prospect for developing bio-safe, durable, and flame retardant cellulose textiles.

Research on high sensitivity piezoresistive sensor based on structural design.

With the popularity of smart terminals, wearable electronic devices have shown great market prospects, especially high-sensitivity pressure sensors, which can monitor micro-stimuli and high-precision dynamic external stimuli, and will have an important impact on future functional development. Compressible flexible sensors have attracted wide attention due to their simple sensing mechanism and the advantages of light weight and convenience. Sensors with high sensitivity are very sensitive to pressure and can detect resistance/current changes under pressure, which has been widely studied. On this basis, this review focuses on analyzing the performance impact of device structure design strategies on high sensitivity pressure sensors. The design of structures can be divided into interface microstructures and three-dimensional framework structures. The preparation methods of various structures are introduced in detail, and the current research status and future development challenges are summarized.