Xinyuhang Zhang,Wei Liao,Yunpeng Wang,Zhongqiang Yang
Graphical A compressible and omnidirectional gripper is constructed using a liquid crystal elastomer foam rod. The compressed gripper enters a slit and grasps and moves hot objects to a safe place, demonstrating its potential for emergency disposal. The reported simple design for gripper construction can enhance the functions of soft robots. Liquid crystal elastomers (LCEs) are considered to be a promising material for the fabrication of soft grippers because of their large and reversible deformations, an LCE gripper with suitable compressibility and omnidirectionality has not yet been developed. To overcome these obstacles, this study utilizes salt template method to fabricate a rod-like LCE foam as gripper. The thickness of the compressible foam can be reduced by up to 77%, temporarily maintaining the deformation and enabling the gripper to pass through slits. The foam was aligned along the long axis and the length of the foam exhibits reversible thermal responsiveness and contract up to 57% along its alignment. Additionally, when the foam approaches a heat source, the generated temperature gradient results in a contraction gradient owing to the low thermal conductivity of the LCE foam. This in turn causes the foam to reversibly bend with a bending angle up to 93° and follow the movement of a heat source omnidirectionally. The developed gripper successfully grasps, moves, and releases hot objects in a cold and safe place, demonstrating its potential for emergency disposal. Thus, LCE foams can be considered suitable materials for novel gripper design and construction.
Gradient refractive index coatings have attracted significant attention in the field of optics due to their antireflective performance over a broad range of wavelength and incident angle. Herein, single layer coatings with various refractive indices were prepared using suspensions of zwitterionically charged chitin nanofibers (ZC-ChNFs) containing different amounts of sodium dihydrogen citrate (SDCA) via layer-by-layer self-assembly. Subsequently, the coatings with different gradient refractive indices were fabricated by stacking the single layers together. Effects of the number of the stacked layers and the changes of gradient refractive index on antireflective performance of the coatings were investigated. The results showed that the gradient refractive index coating with five layers and a quadratic change in refractive index with downward opening yielded gains of 6.6 % at 550 nm and 7.6 % at 650 nm in the transmittance (vertical incidence) of a glass slide, and the transmittance gain of a glass slide coated with this coating reached 8 % at light incident angle of 45°. This work not only demonstrates that SDCA can be used as pore generation agent to reduce refractive index of ChNF coatings, but also offers a feasible pathway to construct gradient refractive index coatings possessing excellent broadband and omnidirectional antireflective performance using ChNFs.
Solar-driven steam generation (SSG) is regarded as a feasible solution to the problem of fresh water scarcity. Although several attempts have been devoted to increase the efficiency of solar-to-steam conversion, it remains difficult to fabricate cost-effective, steady, and multi-angle sunlight-absorbing evaporators from readily available biomass materials. Herein, a novel hierarchical structured SSG evaporator (PDA@Shell-NaClO) is developed through a simple, low-cost, and scalable etching treatment on discarded sea urchin (SU) shells. Attributing to the dedicatedly designed microneedles array structure and porous skeleton structure of the SU shell, this PDA@Shell-NaClO evaporator shows an outstanding average light absorption performance (>90%) in a broad range of angles from 0° to 60° and exceedingly high evaporation rate of 2.81 kg m -2 h −1 under one sun condition. Furthermore, the prepared evaporator also maintains an overall stable evaporation performance and exhibits an excellent durability for a long time of up to two weeks in actual seawater. This full-ocean biomass-based SSG evaporator with plentiful raw material availability offers innovative opportunities for large-scale fresh water production.
危险品化学品经营许可证（带存储）