Ti Gang,Fan Yi,Tang Jian,Niu Chenguang,Xiong Xiaoyan
The morphology of dispersed particles has been proven to have a significant impact on performance of electrorheological (ER) materials, while there is a lack of relevant research on its impact on the properties of electrorheological elastomers (EREs). In this study, the TiO2 particles with spherical, short rod, and long rod shape were fabricated with sol-gel method, and the EREs were prepared with these three kinds of particles as dispersion phase. Particle characterization results show that the rod-shape TiO2 particles with larger average size exhibit a combination of anatase and brookite phase. The viscoelastic properties of three types of EREs under varying strain amplitude and shear frequency were tested. The results indicate that the long rod-shape TiO2 particles filled EREs shows higher storage modulus G′ and higher relative ER effect within the electric field from 0 to 3 kV/mm. The observations indicate the use of rod-shape TiO2 particles in the form of brookite phase may help enhance the ER properties of elastomers. The investigation contributes to the designing, preparation, and application of anisotropic ERE.
Face masks are commonly used to protect an individual’s respiratory system from inhaling fine particulate matter (PM2.5) in polluted air, as well as the airborne pathogens, especially during the ongoing coronavirus disease 2019 (COVID-19) pandemic. However, all conventional masks with anti-PM2.5 function suffer from insufficient facial thermal comfort, particularly in a hot and humid environment. Herein, we demonstrated a novel infrared-transmittance visible-opaque PM2.5 media for radiative cooling utilizing rutile titanium dioxide particle-embedded polyamide 6 (PA6-TiO2). The transmission of visible light and infrared and PM2.5 removal performance of composite media containing a variety of microstructures, such as TiO2 particles of varying sizes, shapes, and contents, were numerically examined to determine the optimal ranges. Then the PA6-TiO2 media was effectively electrospun by controlling the arrangement of fibers and the morphology of TiO2 particles. By transmitting more than 85% of the thermal radiation from the human body and selectively blocking solar irradiance, the developed PA6-TiO2(flower-shaped) media cooled the simulative skin by 10.3°C as compared with commercial masks under strong solar irradiance. Additionally, they demonstrated a high PM2.5 removal efficiency of 95.3%, a low air resistance of 22.5 Pa (at 5.3 cm/s), and a sound water vapor transmission rate of 0.0169 g cm−2 h−1. This study presents an effective strategy for making thermally comfortable anti-PM2.5 masks, which will significantly benefit the public health prevention and control.
It is a challenge to make artificial muscles with tunable stiffness capacities. The key is to develop a composite with tunable stiffness as well as self-healing properties and stretchability. In this work, we design a composite with amorphous TiO2 particles and poly(dimethylsiloxane) (PDMS) matrix cross-linked with metal–ligand interactions. The PDMS matrix enables the composite to have self-healing properties and excellent stretchability, while the interactions between the TiO2 particles can be enhanced by applying an electric field, which provides the composite with an electric field-controlled stiffness. The tunable storage modulus increased by 180% at 4 kV/mm. The stiffness of a simply supported beam increased by 10.8% at 6 kV with respect to that at 0 kV. Based on its tunable stiffness, self-healing properties and stretchability, this composite can mimic many functions of human muscles and has promising applications as an artificial muscle.
危险品化学品经营许可证（带存储）