Radiation synthesis of MXene/Ag nanoparticle hybrids for efficient photothermal conversion of polyurethane films.

Flexible conductive films based on light-to-heat conversion are promising for the next-generation electronic devices. A flexible waterborne polyurethane composite film (PU/MA) with excellent photothermal conversion performance was obtained by combination of PU and silver nanoparticle decorated MXene (MX/Ag). The silver nanoparticles (AgNPs) uniformly decorated on the MXene surface by γ-ray irradiation induced reduction. Because of the synergistic effect of MXene with outstanding light-to-heat conversion efficiency and the AgNPs with plasmonic effect, the surface temperature of the PU/MA-II (0.4%) composite with lower MXene content increased from room temperature to 60.7 °C at 5 min under 85 mW cm-2 light irradiation. Besides, the tensile strength of PU/MA-II (0.4%) increased from 20.9 MPa (pure PU) to 27.5 MPa. The flexible PU/MA composite film shows great potential in the field of thermal management of flexible wearable electronic devices.

A carbon nanotube-based textile pressure sensor with high-temperature resistance.

Textile pressure sensors capable of withstanding high temperatures have attracted increasing interest due to their potential applications in harsh conditions. In this work, a textile pressure sensor with high-temperature resistance was realized based on multi-wall carbon nanotubes (MWCNTs) and quartz fabrics. The textile pressure sensors exhibited low fatigue over 20 000 cyclic loadings. Owing to the high-temperature resistance of MWCNTs and quartz fabrics, the textile sensor can work at temperatures up to 300 °C and can maintain good sensitivity after calcination at 900 °C in N2 for 30 min. This work provides a simple, facile, and inexpensive method for fabricating textile pressure sensors with high-temperature resistance.

Cross-Links-Entanglements Integrated Networks Contributing to Highly Resilient, Soft, and Self-Adhesive Elastomers with Low Hysteresis for Green Wearable Electronics.

Green wearable electronics are attracting increasing attention to eliminate harmful byproducts generated by traditional devices. Although various degradable materials have been explored for green wearable electronics, the development of degradable elastomers with integrated characteristics of low modulus, self-adhesion, high resilient, and low hysteresis remains challenging. In this work, a degradable elastomer poly(1,8-octanediol-co-citrate-co-caprolactone) (POCL) is reported, in which a loosely cross-linked network contains plenty of entangled flexible chains. The coexistence of covalent cross-links and entanglements of long polymer chains endows the elastomer with good resilience and low hysteresis, in addition to low modulus and self-adhesion. Taking advantage of the unique mechanical properties, epidermal strain sensors based on the POCL elastomer were prepared, which exhibited good adhesion to human skin, high sensitivity, high response rate, and excellent fatigue resistance. We also fabricated stretchable electroluminescent devices using this degradable elastomer and demonstrated the recyclability of the nondegradable materials in the electronic device.

Inkjet Printing of a Micro/Nanopatterned Surface to Serve as Microreactor Arrays.

Microreactors are of great importance for chemical reaction screening, nanoparticle synthesis, protein crystallization, DNA detection, organic synthesis, etc. Here, we reported an effective, flexible, and low-cost method for fabricating microreactor arrays by inkjet printing technology. This strategy utilizes the controllable sliding behavior of the three-phase contact line to form hydrophilic-hydrophobic micropatterns for microreactors with sizes low to several hundreds of nanometers. Reactions in the order of 1 × 10-21 mol molecules can be realized in these microreactors, and crystallization processes can also be conducted to synthesize single crystals.

Three-dimensional crimped biodegradable poly(lactic acid) fibers prepared via melt spinning and controlled structural reorganization.

Biodegradable three-dimensional crimped fibers were prepared by the side-by-side composite spinning of poly(lactic acid) (PLA) and low-melting point PLA (LM-PLA). The structural variation of the PLA/LM-PLA composite fibers during dry and wet heat treatment was explored systematically. It is shown that crystallization and disorientation were two key factors for the formation of the three-dimensional crimped structure of PLA/LM-PLA side-by-side composite fibers (SSCF). The wet heat-treated fiber has better crimp performance and fluffiness, and the crimp number, crimp ratio and crimp elasticity ratio of the treated PLA/LM-PLA SSCF with good comprehensive properties are 21 per 25 mm, 31.9% and 81.6%, which are similar to those of industrialized PET/PTT three-dimensional crimped fibers. The results of this study shed light on the development of novel three-dimensional crimped fibers with biodegradability.

Printing 1D Assembly Array of Single Particle Resolution for Magnetosensing.

Magnetosensing is a ubiquitous ability for many organism species in nature. 1D assembly, especially that arranged in single-particle-resolution regulation, is able to sense the direction of magnetic field depending on the enhanced dipolar interaction in the linear orientation. Inspired by the magnetosome structure in magnetotactic bacteria, a 1D assembly array of single particle resolution with controlled length and well-behaved configuration is prepared via inkjet printing method assisted with magnetic guiding. In the fabrication process, chains in a "tip-to-tip" regulation with the desired number of particles are prepared in a confined tiny inkjet-printed droplet. By adjusting the receding angle of the substrate, the assembled 1D morphology is kept/deteriorated depending on the pinning/depinning behavior during ink evaporation, which leads to the formation of well-behaved 1D assembly/aggregated dot assembly. Owing to the high-aspect-ratio characteristic of the assembled structure, the as-prepared 1D arrays can be used for magnetic field sensing with anisotropic magnetization M// /M⊥ up to 6.03.

Direct-Writing Multifunctional Perovskite Single Crystal Arrays by Inkjet Printing.

Perovskite single-crystalline microplate arrays are directly achieved in large scale by inkjet printing, which present high performance lasing property with quality factors up to 863 and RGB (red-green-blue) emission. This facile, nonlithographic method makes its promising applications on multi-integrated coherent light sources and other high-performance integrated optoelectronic applications.

Bio-inspired photonic crystals with superwettability.

Photonic crystals (PCs) have attracted enormous research interest due to their unique light manipulation and potential applications in sensing, catalysts, detection, displays, solar cells and other fields. In particular, many novel applications of PCs are derived from their surface wettability. Generally, the wettability of PCs is determined by a combination of its surface geometrical structures and surface chemical compositions. This review focuses on the recent developments in the mechanism, fabrication and application of bio-inspired PCs with superwettability. It includes information on constructing superwetting PCs based on designing the topographical structure and regulating the surface chemical composition, and information on extending the practical applications of superwetting PCs in humidity/oil/solvent sensing, actuating, anti-fouling and liquid-impermeable surface, chemical detection, etc.

Single-material solvent-sensitive actuator from poly(ionic liquid) inverse opals based on gradient dewetting.

A novel and reversible single-material solvent-sensitive actuator was developed from poly(ionic liquid) inverse opals based on a gradient wetting/dewetting process combining the strong hydrogen bonding interaction between the solvent and polymer. This study will provide an important insight for the design and fabrication of novel-type solvent-actuator materials.

Sliding three-phase contact line of printed droplets for single-crystal arrays.

Controlling the behaviours of printed droplets is an essential requirement for inkjet printing of delicate three-dimensional (3D) structures or high-resolution patterns. In this work, molecular deposition and crystallization are regulated by manipulating the three-phase contact line (TCL) behaviour of the printed droplets. The results show that oriented single-crystal arrays are fabricated based on the continuously sliding TCL. Owing to the sliding of the TCL on the substrate, the outward capillary flow within the evaporating droplet is suppressed and the molecules are brought to the centre of the droplet, resulting in the formation of a single crystal. This work provides a facile strategy for controlling the structures of printed units by manipulating the TCL of printed droplets, which is significant for realizing high-resolution patterns and delicate 3D structures.

Simultaneous synthesis/assembly of anisotropic cake-shaped porphyrin particles toward colloidal microcrystals.

The one-step synthesis/assembly of a cake-shaped porphyrin colloidal microcrystal with tailored height-diameter was demonstrated based on interfacial assembly and the water-droplet template. The as-fabricated anisotropic colloidal crystals showed special optic properties and enhanced optic-limiting behavior.

Controllable printing droplets for high-resolution patterns.

Inkjet printing has attracted wide attention due to the important applications in fabricating biological, optical, and electrical devices. During the inkjet printing process, the solutes prefer to deposit along the droplet periphery and form an inhomogeneous morphology, known as the coffee-ring effect. Besides, the feature size of printed dots or lines of conventional inkjet printing is usually limited to tens or even hundreds of micrometers. The above two issues greatly restrict the extensive application of printed patterns in high-performance devices. This paper reviews the recent advances in precisely controlling the printing droplets for high-resolution patterns and three-dimensional structures, with a focus on the development to suppress the coffee-ring effect and minimize the feature size of printed dots or lines. A perspective on the remaining challenges of the research is also proposed.