A Comparative Study on the Phase Structure, Optical and NIR Reflectivity of BaFe12O19 Nano-Pigments by the Traditional and Modified Polyacrylamide Gel Method

Barium hexaferrite (BaFe12O19) nano- pigment is a pigment with high near infrared reflection in the wavelength range of 1400-2500 nm. The BaFe12O19 nano- pigments were synthesized by the traditional and modified polyacrylamide gel method and characterized by thermogravimetric and differential scanning calorimetry (TG-DSC) analyses, X-ray powder diffraction (XRD), fourier transform infrared (FTIR), transmission electron microscopy (TEM), and UV-Visible spectrophotometer. The physicochemical properties of BaFe12O19 nanopigments are strongly dependent on the synthesis route. The introduction of carbon particles into the BaFe12O19 precursor accelerates the formation of BaFe12O19 phase, reduces its particle diameter and changes its color properties. The modified polyacrylamide gel method makes it possible to obtain a high efficient near infrared reflection BaFe12O19 nano- pigments with a solar reflectance SR>90%. The high near infrared reflection makes BaFe12O19 nano- pigments have potential applications in the field of heat shielding.

Mixed-dimensional MXene-hydrogel heterostructures for electronic skin sensors with ultrabroad working range

Skin-mountable microelectronics are garnering substantial interest for various promising applications including human-machine interfaces, biointegrated devices, and personalized medicine. However, it remains a critical challenge to develop e-skins to mimic the human somatosensory system in full working range. Here, we present a multifunctional e-skin system with a heterostructured configuration that couples vinyl-hybrid-silica nanoparticle (VSNP)–modified polyacrylamide (PAM) hydrogel with two-dimensional (2D) MXene through nano-bridging layers of polypyrrole nanowires (PpyNWs) at the interfaces, featuring high toughness and low hysteresis, in tandem with controlled crack generation and distribution. The multidimensional configurations endow the e-skin with an extraordinary working range (2800%), ultrafast responsiveness (90 ms) and resilience (240 ms), good linearity (800%), tunable sensing mechanisms, and excellent reproducibility. In parallel, this e-skin platform is capable of detecting, quantifying, and remotely monitoring stretching motions in multiple dimensions, tactile pressure, proximity sensing, and variations in temperature and light, establishing a promising platform for next-generation smart flexible electronics.