No abstract

Two liquid crystal diepoxides [1,4-phenylene bis(4-(2,3-epoxypropoxy)benzoate) (A) and 4,4′diglycidyloxydiphenyl (B)] were cured with a diamine [4,4′-diaminobiphenyl (C)] in the nematic phase to obtain liquid crystalline thermoset (LCT) materials. The systems were studied using different curing conditions and different ratios of the compounds. The mechanical properties were investigated by stress/ strain experiments to determine ultimate properties (break strength and elongation at break) and dynamic mechanical thermal analysis (DMTA) to determine small strain properties as a function of temperature. An A/C mole ratio of 4/1 gave materials with the best combination of high strength and percent elongation. The addition of a small amount of diepoxide B to the system (with a mole ratio of A/B ) 4/1) improves the mechanical properties. Dynamic mechanical thermal analysis shows that increasing diamine content or curing time increases the cross-linking density. Macroscopic orientation of the LCTs was achieved by curing the mixtures in the presence of a magnetic field. The samples show that the tensile modulus, break strength, elongation at break, and the storage modulus below the glass transition all increase by a factor of about 2.

The continuous real-time monitoring of human physical health is crucial in the pursuit in a high quality of modern life and has attracted a great deal of attention in research on advanced wearable pressure sensors. However, most of the previous sensors have been built on flexible solid substrate that is not air permeable, leading to skin inflammation after a long-term skin attachment. Herein, we have developed a flexible and breathable pressure sensor based on nonwoven fabrics decorated with MXene as fabric electrodes and an ionic gel as a fabric electrolyte. Due to the advantages of both the supercapacitive iontronic sensing mechanism and the hierarchical structures of the nanoscaled stacked MXene wrapping on the microscale fabric framework, the optimized pressure sensor exhibits a high sensitivity of 31.40 kPa −1 (0−10 kPa), a wide detection range of up to 80 kPa, and a short response time of ∼45 ms as well as excellent repeatability and cyclability. The fabric sensor can be seamlessly woven into textiles for practical wearable sensing and is capable of detecting subtle arterial pulse beats at the wrist and weak breathing rhythms at the chest without affecting the comfort of the wearer. The incorporation of the developed fabric sensors into commonly used clothing through a facile manufacturing process is promising to achieve a comfortable health diagnosis.

A novel gear-shaped micromixer utilizing inertio-elastic flow instability and its application to the continuous synthesis of silica nanoparticle.