The printed circuit board (PCB) contains nearly 28% metals that are abundant non-ferrous metals such as Cu, Al, Sn, etc. The purity of precious metals in PCBs is more than 10 times higher than that of rich-content minerals. Therefore, recycling of PCBs is an important subject not only from the treatment of waste but also from the recovery of valuable materials. Chemical and mechanical methods are two traditional recycling processes for waste PCBs. However, the prospect of chemical methods will be limited since the emission of toxic liquid or gas brings secondary pollution to the environment during the process. Mechanical processes, such as shape separation, jigging, density-based separation, and electrostatic separation have been widely utilized in the recycling industry. But, recycling of waste PCBs is only beginning. In this study, a total of 400 kg of waste PCBs was processed by a recycle technology without negative impact to the environment. The technology contained mechanical two-step crushing, corona electrostatic separating, and recovery. The results indicated that (i) two-step crushing was an effect process to strip metals from base plates completely; (ii) the size of particles between 0.6 and 1.2 mm was suitable for corona electrostatic separating during industrial application; and (iii) the nonmetal of waste PCBs attained 80% weight of a kind of nonmetallic plate that expanded the applying prospect of waste nonmetallic materials.

Stretchable and flexible sensors attached onto the surface of the human body can perceive external stimuli, thus attracting extensive attention due to their lightweight, low modulus, low cost, high flexibility, and stretchability. Recently, a myriad of efforts have been devoted to improving the performance and functionality of wearable sensors. Herein, this review focuses on recent remarkable advancements in the development of flexible and stretchable sensors. Multifunction of these wearable sensors is realized by incorporating some desired features (e.g., self-healing, self-powering, linearity, and printing). Next, focusing on the characteristics of carbon nanomaterials, nanostructured metal, conductive polymer, or their hybrid composites, two major strategies (e.g., materials that stretch and structures that stretch) and diverse design approaches have been developed to achieve highly flexible and stretchable electrodes. Strain sensing performances of recently reported sensors indicate that the appropriate choice of geometric engineering as well as intrinsically stretchable materials is essential for high-performance strain sensing. Finally, some important directions and challenges of a fully sensor-integrated wearable platform are proposed to realize their potential applications for human motion monitoring and human-machine interfaces.

The synthesis and properties of two soluble, weakly coordinating derivatives of the tetrakis(perfluoroaryl)borate anion B(4-C6F4TBS)4 - and B(4-C6F4TIPS)4 - (TBS = tert-butyldimethylsilyl and TIPS = triisopropylsilyl) are reported. Reaction of the trityl salts of the above anions with a variety of zirconium and thorium L2MMe2 complexes in benzene or toluene affords the cationic ion-paired methyl complexes L2MMe+X- or the corresponding hydrido complexes L2MH+X- (L2 = bis(cyclopentadienyl)- or cyclopentadienylamido-type ligand) when the reaction is carried out under dihydrogen. The solid state structure of the complex (Me5Cp)2ThMe+B(C6F5)4 - has been characterized by X-ray diffraction. The B(C6F5)4 --based zirconocenium methyl complexes L2MMe+ are unstable at room temperature with respect to, among other factors, intramolecular C−H activation of the ligand framework. In general, the thermal stabilities of the B(C6F4TBS)4 -- and B(C6F4TIPS)4 --derived complexes are greater than those of the corresponding B(C6F5)4 -- and MeB(C6F5)3 --derived analogues. The relative coordinative tendencies of MeB(C6F5)3 -, B(C6F5)4 -, B(C6F4TBS)4 -, and B(C6F4TIPS)4 - are estimated from the solution spectroscopic information and the structural dynamics of the ion-pairs and follow the order MeB(C6F5)3 - > B(C6F4TBS)4 - ≈ B(C6F4TIPS)4 - > B(C6F5)4 -. The coordination of the neutral metallocene precursors to the cationic metallocenes is found to compete with counteranion coordination. Arene solvent coordination to the zirconium constrained geometry cation [(Me4Cp)SiMe2(NtBu)]ZrMe+ is also observed when B(C6F5)4 - is the counteranion. (1,2-Me2Cp)2ZrMe+B(C6F4TBS)4 - undergoes slow decomposition under an inert atmosphere to afford [(1,2-Me2Cp)2ZrF]2(μ-F)+B(C6F4TBS)4 -, which has been characterized by X-ray diffraction. The olefin polymerization activity and thermal stability of the zirconocene catalysts reaches a maximum when B(C6F4TBS)4 - and B(C6F4TIPS)4 - are used as counteranions. The polymerization activity of the zirconium constrained geometry complex also reaches a maximum in aromatic solvents when B(C6F5)4 - is used as the counteranion, apparently due to solvent coordination.

ABSTRACT:The emergence of stretchable electronics and its potential integration with textiles have highlighted a challenge: textiles are wearable and washable, but electronic devices are not. Many stretchable conductors have been developed to enable wearable active textiles, but little has been done to make them washable. Here we demonstrate a new class of stretchable conductors that can endure wearing and washing conditions commonly associated with textiles.Such a conductor consists of a hydrogel, a dissolved hygroscopic salt, and a butyl rubber coating.The hygroscopic salt enables ionic conduction, and matches the relative humidity of the hydrogel 2 to the average ambient relative humidity. The butyl rubber coating prevents the loss and gain of water due to the daily fluctuation of ambient relative humidity. We develop the chemistry of dip coating the butyl rubber onto the hydrogel, using silanes to achieve both the crosslink of the butyl rubber and the adhesion between the butyl rubber and the hydrogel. We test the endurance of the conductor by soaking it in detergent while stretching it cyclically, and by machinewashing it. The loss of water and salt is minimal. It is hoped that these conductors open applications in healthcare, entertainment, and fashion.3

Spent lithium ion battery (LIB) recovery is becoming quite urgent for environmental protection and social needs due to the rapid progress in LIB industries. However, recycling technologies cannot keep up with the exaltation of the LIB market. Technological improvement of processing spent batteries is necessary for industrial application. In this paper, spent LIB recovery processes are classified into three steps for discussion: gathering electrode materials, separating metal elements, and recycling separated metals. Detailed discussion and analysis are conducted in every step to provide beneficial advice for environmental protection and technology improvement of spent LIB recovery. Besides, the practical industrial recycling processes are introduced according to their advantages and disadvantages. And some recommendations are provided for existing problems. Based on current recycling technologies, the challenges for spent LIB recovery are summarized and discussed from technological and environmental perspectives. Furthermore, great effort should be made to promote the development of spent LIB recovery in future research as follows: (1) gathering high-purity electrode materials by mechanical pretreatment; (2) green metals leaching from electrode materials; (3) targeted extraction of metals from electrode materials.