Lixing Dai

Addressing the critical issues of inevitable agglomeration and unsatisfactory photocatalytic efficiency inherent to powdered photocatalysts during water treatment, the idea to develop a robust nanofiber membrane carrier that can achieve uniform loading of photocatalysts and enhance their activity is valuable. The modified polyacrylonitrile (P-CPAN) was synthesized first by pomegranate peel carbon dots (PCDs) with acrylonitrile (AN) and acrylic acid (AA) through the in situ polymerization, then the hierarchical composite membrane, i.e., TP/CT@P-CPAN, was fabricated via electrospinning followed by a subsequent preimpregnation/solvothermal synthesis method. Compared with the reference sample, i.e., titanium dioxide (CT) powder, the heterojunctional TiO2@PCDs (TP) powder formed by the combination of TiO2 and PCDs has better photocatalytic ability, as TP could significantly expand the light absorption range to the visible-light region and reduce the recombination of photoinduced electron–hole pairs. Both PCDs and −COOH groups on the surface of P-CPAN nanofibers were suitable anchor points for amorphous CT during preimpregnation, TP and CT crystals through solvothermal synthesis could then attach firmly on the membrane. Hence, the TP/CT@P-CPAN membrane demonstrated good photocatalytic performance and durability. Even after 4 h of ultrasonic treatment, no significant shedding of the supported photocatalyst was observed. It can remain relatively stable even under acidic (pH = 2), alkaline (pH = 12), and high-salinity (10 g·L–1) conditions. Research on this kind of TP/CT@P-CPAN material that can be applied to complex usage environments has certain reference value for the development of fiber membrane-based photocatalyst materials.

Elastic polyester fibers play an important role in daily textiles, but to raise the elasticity of regular polyethylene terephthalate (PET) fibers is still a challenge. Herein, inspired by springs, carboxylic helical carbon nanotubes (HCNTs‐COOH) are used as nanosprings to graft onto PET backbone to produce PET@HCNTs fibers (PETHf). Under single‐cycle loading tests, PETHf‐0.5 (containing 0.5% HCNTs‐COOH) achieves complete recovery at 5% elongation, with elastic recovery rate increased by 16.3% relative to neat PET fiber (PETf), and by 13.4% relative to the blend fiber of PET containing the same amount of HCNTs. After 10‐cycle loading tests with increasing elongation to 10%, the elastic recovery rate still reaches 62.6%, 21.3% higher than that of PETf, and 19.2% higher than that of the PET blend fiber. Furthermore, the fabric cylinder folding test indicates that PETHf‐0.5 has much better shape recovery than PETf. Application of PETHf in badminton strings shows a 16% increase in the bounce height of shuttlecock compared with nylon‐based commercial badminton strings, further confirming its excellent elasticity. Overall, this work provides a practical and effective strategy for enhancing the elasticity of regular PET fibers.

A strain sensor with high sensitivity and a wide working range is urgently required owing to its potential applications in wearable electronic devices. Nevertheless, high sensitivity, which includes a high gauge factor (GF) and a low detection limit, requires a noticeable structural variation even at a tiny deformation, while a wide working range requires maintaining morphological integrity under a large strain. The contradictory performances lead to a huge challenge to simultaneously acquire the aforementioned comprehensive performance. Herein, we prepared a twisted fiber-based strain sensor (TFSS) composed of a thermoplastic polyurethane (TPU)/silver nanoparticle (AgNP) fiber and a TPU/carbon nanotube (CNT) fiber. The special twisting structure and the synergistic effect of the different conductive materials endow TFSS with a high GF of 1.05 × 10⁵ within a strain range of 250 ∼ 300%, ultralow detection limit (0.02% strain), large detection range (up to 300% strain), short response time (60 ms), and excellent sensing stability and durability (4000 stretching/releasing cycles under 50% strain). Moreover, the strain sensor can be used for diverse human movement recognition, microexpression detection, pulse/breath monitoring, and speech recognition, offering a promising strategy for designing high-performance and smart wearable devices.

With the rapid development of intelligent electronic devices, there is a growing demand for flexible strain sensors with a fast response, high sensitivity, a large sensing range, a low detection limit, and good repeatability simultaneously. However, combining the excellent sensing performances into one sensor via special structures remains a great challenge. Herein, inspired by the special spring deformation process from contact to separation of the helixes, a strategy to build a fiber based strain sensor with tightly interconnected helixes has been presented. The sensor is composed of a spring-like polyvinyl alcohol (PVA) conductive fiber wound around a highly elastic substrate. The spring-like structure endows the sensor for stretching strain with a wide sensing range (200% strain), an ultralow detection limit (0.01% strain), and high repeatability (12 000 cycles). More importantly, the sensor exhibits high sensitivity (a gauge factor of about 66 in the small strain range) and a fast response (∼42 ms) due to the huge resistance difference caused by the separation process of the helixes from the tight contact state. Taking advantage of the superior sensing performance, the sensor can be applied for speech recognition, micro-expression detection, and pulse/respiration monitoring. In particular, the real-time monitoring applications for a series of complicated human activities have been developed to help infants, elderly people, and people with disabilities. This work will provide a universal and effective strategy for designing high-performance intelligent wearable devices.

Polyvinyl alcohol (PVA) aerogel fibers exhibit encouraging potential as thermal insulation materials, but their hydrophilicity easily results in severe collapse of the aerogel pore structure. Therefore, hydrophobic modification of PVA aerogel fibers is of significance to their structural stability and durability. Here, a novel process was proposed to continuously generate high‐hydrophobic PVA‐based composite aerogel fibers containing polymethylsilsesquioxane (PMSQ) by introducing methyltrimethoxysilane (MTMS) through freeze‐thawing, freeze‐spinning, and freeze‐drying processes. With optimized freezing time and MTMS content, the PVA‐based composite solution showed good spinnability, and the resulting PVA/PMSQ (PVASi) aerogel fibers were endowed with markedly enhanced hydrophobicity and excellent weavability due to sufficient mechanical properties. Most importantly, the aerogel fibers possessed excellent hydrophobic structural stability after 12 h or 50‐cycle soaking and 50‐cycle washing. Benefiting from these superior characteristics, the aerogel fibers were demonstrated to be effective thermal insulators in high humidity (>90% relative humidity) and after washing for 50 cycles.