High Value-Added Reutilization of Waste-Printed Circuit Boards Non-Metallic Components in Sustainable Polymer Composites.

The reutilization non-metallic components from a waste-printed circuit board (WPCB) has become one of the most significant bottlenecks in the comprehensive reuse of electronic wastes due to its low value and complex compositions, and it has received great attention from scientific and industrial researchers. To effectively address the environmental pollution caused by inappropriate recycling methods, such as incineration and landfill, extensive efforts have been dedicated to achieving the high value-added reutilization of WPCB non-metals in sustainable polymer composites. In this review, recent progress in developing sustainable polymer composites based on WPCB non-metallic components was systematically summarized. It has been demonstrated that the WPCB non-metals can serve as a promising reinforcing and functional fillers to significantly ameliorate some of the physical and chemical properties of polymer composites, such as excellent mechanical properties, enhanced thermal stability, and flame retardancy. The recovery strategies and composition of WPCB non-metals were also briefly discussed. Finally, the future potentials and remaining challenges regarding the reutilization of WPCB non-metallic components are outlined. This work provides readers with a comprehensive understanding of the preparation, structure, and properties of the polymer composites based on WPCB non-metals, providing significant insights regarding the high value-added reutilization of WPCB non-metals of electronic wastes.

A hierarchical system of covalent and dual non-covalent crosslinks promotes the toughness and self-healing properties of polymer hydrogels.

While it is challenging to simultaneously achieve both high mechanical performance and self-healing ability within one polymer hydrogel network, we, herein, synthesized a novel class of hydrogels based on a combination of chemical and dual non-covalent crosslinks via micellar polymerization of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, end-capped by 2-hydroxyethyl methacrylate (IPDI-HEMA), with acrylamide (AM). The prepared hydrogels were demonstrated to possess a tensile elongation at a break of at least 1900%, a fracture energy of 138.4 kJ m-3, and remarkable self-healing behaviors (e.g., a strong self-healing ability achieved at ambient temperature without the need for any stimulus or healing agent). The multiple crosslinks developed in this study for one polymer hydrogel network are significant steps to construct the desired functional hydrogels with excellent self-healing and mechanical properties.

Highly tough and rapid self-healing dual-physical crosslinking poly(DMAA-co-AM) hydrogel.

Introducing double physical crosslinking reagents (i.e., a hydrophobic monomer micelle and the LAPONITE® XLG nano-clay) into the copolymerization reaction of hydrophilic monomers of N,N-dimethylacrylamide (DMAA) and acrylamide (AM) is reported here by a thermally induced free-radical polymerization method, resulting in a highly tough and rapid self-healing dual-physical crosslinking poly(DMAA-co-AM) hydrogel. The mechanical and self-healing properties can be finely tuned by varying the weight ratio of nanoclay to DMAA. The tensile strength and elongation at break of the resulting nanocomposite hydrogel can be modulated in the range of 7.5-60 kPa and 1630-3000%, respectively. Notably, such a tough hydrogel also exhibits fast self-healing properties, e.g., its self-healing rate reaches 48% and 80% within 2 and 24 h, respectively.

Bismuth chelate as a contrast agent for X-ray computed tomography.

BACKGROUNDS: Due to the unexpected side effects of the iodinated contrast agents, novel contrast agents for X-ray computed tomography (CT) imaging are urgently needed. Nanoparticles made by heavy metal elements are often employed, such as gold and bismuth. These nanoparticles have the advantages of long in vivo circulation time and tumor targeted ability. However, due to the long residence time in vivo, these nanoparticles may bring unexpected toxicity and, the preparation methods of these nanoparticles are complicated and time-consuming. METHODS: In this investigation, a small molecular bismuth chelate using diethylenetriaminepentaacetic acid (DPTA) as the chelating agent was proposed to be an ideal CT contrast agent. RESULTS: The preparation method is easy and cost-effective. Moreover, the bismuth agent show better CT imaging for kidney than iohexol in the aspect of improved CT values. Up to 500 µM, the bismuth agent show negligible toxicity to L02 cells and negligible hemolysis. And, the bismuth agent did not induce detectable morphology changes to the main organs of the mice after intravenously repeated administration at a high dose of 250 mg/kg. The pharmacokinetics of the bismuth agent follows the first-order elimination kinetics and, it has a short half-life time of 0.602 h. The rapid clearance from the body promised its excellent biocompatibility. CONCLUSIONS: This bismuth agent may serve as a potential candidate for developing novel contrast agent for CT imaging in clinical applications.

Long and Ultrastable All-Inorganic Single-Crystal CsPbBr3Microwires: One-Step Solution In-Plane Self-Assembly at Low Temperature and Application for High-Performance Photodetectors.

As ideal building blocks for optoelectronic devices, one-dimensional (1D) single-crystal perovskite microwires (MWs) have received widespread attention due to their unique physical and chemical properties. Herein, a one-step solution in-plane self-assembly method is proposed to directly grow millimeter-long CsPbBr3 MWs with superior crystal quality at atmospheric environment. This method effectively avoids the use of toxic antisolvents. Furthermore, a MW-based photodetector is successfully fabricated, showing high photoresponsivity (20 A/W) and fast response (less than 0.3 ms). The stability of the photodetector is also confirmed by aging MW in air for 60 days, which shows a negligible change of photocurrent from 1.29 to 1.25 nA (-3 V) under the same experimental conditions. This work provides a low-cost and fast synthesis method for the preparation of single-crystal perovskite MWs and demonstrates their potential application for high-performance and stable photoelectronic device.

InGaN Nanorods Decorated with Au Nanoparticles for Enhanced Water Splitting Based on Surface Plasmon Resonance Effects.

Photoelectrochemical (PEC) water splitting has great application potential in converting solar energy into hydrogen energy. However, what stands in the way of the practical application of this technology is the low conversion efficiency, which can be promoted by optimizing the material structure and device design for surface functionalization. In this work, we deposited gold nanoparticles (Au NPs) with different loading densities on the surface of InGaN nanorod (NR) arrays through a chemical solvent route to obtain a composite PEC water splitting system. Enhanced photocatalytic activity, which can be demonstrated by the surface plasmon resonance (SPR) effect induced by Au NPs, occurred and was further confirmed to be associated with the different loading densities of Au NPs. These discoveries use solar water splitting as a platform and provide ideas for exploring the mechanism of SPR enhancement.

The use of amphiphilic copolymer in the solid dispersion formulation of nimodipine to inhibit drug crystallization in the release media: Combining nano-drug delivery system with solid preparations.

Solid dispersion is a widely used method to improve the dissolution and oral bioavailability of water-insoluble drugs. However, due to the strong hydrophobicity, the drug crystallization in the release media after drug dissolution and the resulted decreased drug absorption retards the use of solid dispersions. It is widely known that the amphiphilic copolymer can encapsulate the hydrophobic compounds and help form stable nano-dispersions in water. Inspired by this, we tried to formulate the solid dispersion of nimodipine by using amphipathic copolymer as one of the carriers. Concerning the solid dispersions, there are many important points involved in these formulations, such as the miscibility between the drug and the carriers, the storage stability of solid dispersions, the dissolution enhancement and so on. In this study, a systemic method is proposed. In details, the supersaturation test and the glass transition temperature (Tg) measurement to predict the crystallization inhibition, the ratios of different components and the storage stability, the interactions among the components were investigated in detail by nuclear magnetic resonance (1H NMR) and isothermal titration calorimetry (ITC) and, the final dissolution and oral bioavailability enhancement. It was found that the amphiphilic copolymer used in the solid dispersion encouraged the formation the drug loading micelles in the release media and, finally, the problem of drug crystallization in the dissolution process was successfully solved.

Preparation and Properties of Polydimethylsiloxane (PDMS)/Polyethylene Glycol (PEG)-Based Amphiphilic Polyurethane Elastomers.

Amphiphilic polyurethane elastomers (APUE) were synthesized using a two-step polyaddition reaction based on the hydroxyl-terminated polydimethylsiloxane (PDMS) and polyethylene glycol (PEG) soft segments with the molecular weights (Mw's) of 2000 and 1000, respectively. The effects of the PDMS/PEG contents on the properties and structures of the APUE were investigated. It was found that the APUE possessed high elongation, moderate tensile strength, and good thermal properties. In addition, the APUE showed tunable oxygen permeability (Dk) and water vapor transmission rate (WVTR), and a similar WVTR to that of skin could be obtained for the optimized sample (APUE2). Importantly, APUE also exhibited excellent antibacterial efficacy against two kinds of bacteria along with impressive cytocompatibility. All of the results demonstrated that the synthesized APUE will hold substantial potential for biomaterial applications.

Self-healing zwitterionic sulfobetaine nanocomposite hydrogels with good mechanical properties.

The development of zwitterionic hydrogels possessing both excellent self-healing and mechanical properties is of great significance. Herein, a class of zwitterionic sulfobetaine nanocomposite hydrogels was prepared by UV-initiated copolymerisation of zwitterionic sulfobetaine monomer N,N-dimethyl-N-(3-methacrylamidopropyl)-N-(3-sulfopropyl) ammonium betaine (DMAPMAPS) and 2-hydroxyethyl methacrylate (HEMA) in the presence of exfoliated clay platelets uniformly dispersed in an aqueous medium. The effects of the hydrogel compositions, including the DMAPMAPS/HEMA mass ratio and the amount of clay, on the self-healing behaviors and mechanical properties of the nanocomposite hydrogels were investigated. The results indicate that the fabricated zwitterionic sulfobetaine nanocomposite hydrogels can autonomously repair incisions or cracks at ambient temperature without the need for any stimulus and possess excellent mechanical properties.

Preparation and characterization of protein-resistant hydrogels for soft contact lens applications via radical copolymerization involving a zwitterionic sulfobetaine comonomer.

We aimed to introduce hydrophilic sulfobetaine-type zwitterionic groups to macromolecular chains of copolymers to construct novel copolymer hydrogels with anti-protein-fouling performance that could be used as soft contact lens (SCL) materials. Using hydroxyethyl methacrylate (HEMA), N-vinyl pyrrolidinone (NVP) and sulfobetaine methacrylate (SBMA) as comonomers, several copolymer hydrogels with different SBMA contents, poly(HEMA-NVP-SBMA), are synthesized via radical copolymerization in an aqueous phase. Surface chemistry, structural morphologies, water contact angle (WCA), equilibrium water content (EWC), visible light transmittance and tensile mechanical properties are investigated. The prepared hydrogels exhibit a closed-type porous structure. With increasing SBMA content in the comonomer mixture, the prepared copolymer hydrogel pore size gradually increases up to the micron level, WCA tends to decrease, EWC tends to increase, and visible light transmittance slightly increases, but their tensile mechanical properties decline. The amounts of protein Lyz and BSA adsorbed on the copolymer hydrogels and on commercially available EASY DAY® SCLs as a control are also determined by protein adsorption tests. The amount of protein adsorbed on the copolymer hydrogel decreases with increasing SBMA content. For the hydrogel prepared using the comonomer mixture with 5.0 wt % SBMA, the amount of adsorbed Lyz is 0.91 µg/cm2, which corresponds to only 56.8% of the amount adsorbed on EASY DAY® SCLs. Thus, novel SCL materials with high water content and excellent anti-protein-fouling performance were efficiently constructed by introducing sulfobetaine-type zwitterionic groups into a traditional polymer hydrogel system.

An intermolecular quadruple hydrogen-bonding strategy to fabricate self-healing and highly deformable polyurethane hydrogels.

The development of hydrogels possessing both excellent self-healing and mechanical properties in hydrogel science due to their tight relationship with the many potential application scopes is of great significance. Herein, a novel class of polyurethane (PU) hydrogels with intermolecular quadruple hydrogen-bonding interactions were designed and fabricated by the copolymerization of poly(ethylene glycol) methacrylate end-capped urethane ether prepolymer (PU-PEGMA) with 2-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-yl)ureido)ethyl methacrylate (SCMHBMA) bearing the 2-ureido-4-pyrimidone (UPy) unit. The effects of the SCMHBMA content on the self-healing behaviors and mechanical properties of the PU hydrogels were investigated. The results indicate that the fabricated PU hydrogels can autonomously and rapidly repair occurring incisions or cracks at ambient temperature without the need for any stimulus and possess high deformability under both tensile and compressive stress and strong recoverability upon removal of stress, thus exhibiting outstanding self-healing, elasticity, robustness and toughness. The presence of UPy units in PU macromolecular chains is a decisive factor endowing the PU hydrogels with these characteristics.