The first effective organopolymerization of the biorenewable “non‐polymerizable” γ‐butyrolactone (γ‐BL) to a high‐molecular‐weight metal‐free recyclable polyester is reported. The superbase ...tert‐Bu‐P4 is found to directly initiate this polymerization through deprotonation of γ‐BL to generate reactive enolate species. When combined with a suitable alcohol, the tert‐Bu‐P4‐based system rapidly converts γ‐BL into polyesters with high monomer conversions (up to 90 %), high molecular weights (Mn up to 26.7 kg mol−1), and complete recyclability (quantitative γ‐BL recovery).
Recyclable and renewable: The fast organopolymerization of the biorenewable non‐strained γ‐butyrolactone has led to a high‐molecular‐weight metal‐free polyester with complete recyclability. The monomer has been long believed to be a non‐polymerizable monomer because of its stable five‐membered ring structure.
The catalyst recovery is the major concern in commercialization of photocatalysts for the industrial effluent treatment process. To overcome this major issue, Fe2O3 based magnetic photocatalytic ...heterostructure ɣ-Fe2O3/FeTiO3 nanocomposite was synthesized by hydrothermal method. Fe2O3 is the cheapest visible active magnetic photocatalytic material, but it has the limitation of fast e−/h + recombination. Titanium (Ti) was loaded on γ-Fe2O3 to overcome this issue. The loaded Ti has grown as FeTiO3 on the surface of ɣ-Fe2O3 nanocrystals and emerged as heterostructure ɣ- Fe2O3/FeTiO3 nanocomposites, which was confirmed by XRD and TEM results. The loading concentration of Ti on γ-Fe2O3 was optimized to achieve the maximum photocatalytic efficiency without compromising the magnetic property of γ-Fe2O3 to facilitate the magnetic separation. DRS-UV spectra revealed the strong visible light response of γ- Fe2O3/FeTiO3 nanocomposite. The photocatalytic efficiencies of the synthesized materials were evaluated using methylene blue (MB) as a model pollutant under sunlight. The built-in electric field between p-n junction between FeTiO3 and Fe2O3 and type II charge transfer mechanism extended the lifetime of the charge carriers at the heterojunction of γ- Fe2O3/FeTiO3, which was confirmed by PL spectra. The vibrating sample magnetometer (VSM) study revealed the decreasing magnetization, coercivity (Hc), and retentivity (Mr) of γ-Fe2O3 with increasing concentration of Ti. 92% of the used-up 20 wt% Ti loaded γ-Fe2O3/FeTiO3 magnetic nanocomposite was recovered from the treated wastewater using an electromagnet. Both magnetic properties and efficiency of the nanocomposite increased up to 20 wt% of Ti loading, beyond that decreased due to the increasing composition of antiferromagnetic FeTiO3 and the increasing number of defect sites as recombination centers. Hence, 20 wt% loading of Ti was concluded as the optimum to enhance the efficiency and to retain the magnetic properties. This work aims the commercialization of magnetic photocatalytic materials for the industrial effluent treatment.
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•γ-Fe2O3/FeTiO3 heterostructured magnetic nanocomposite was synthesized by hydrothermal method.•The lifetime of the charge carriers was extended by p-n junction and type II charge transfer mechanism.•γ-Fe2O3 catalyst recovery decreased beyond 20 wt% of Ti loading due to the increase of antiferromagnetic FeTiO3.•Complete degradation of methylene blue dye was achieved within 2 h under solar light.•92% catalyst recovery was attained for 20 wt% Ti loaded γ-Fe2O3/FeTiO3 magnetic nanocomposite.
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•The polyurethane composites with multiple functions were successfully prepared.•The reversible network endowed the composites with ability to heal and recycle.•The composites had ...superior energy storage ability and photo-thermal conversion.
Development of recyclable and self-repairing phase-change materials, which enable renewable energy storage and sustainable development, is critical for the efficient utilisation of solar energy. Hence, we herein fabricated form-stable, reversible cross-linked polyurethane phase-change materials composites (DPCM-x) with excellent recyclability, outstanding self-healing ability (93.1%) and superior photo-thermal conversion efficiency (87.9%). Furan-modified polydopamine particles (f-PDAPs), which serve as cross-linkers and photo-thermal fillers, were incorporated into maleimide-terminated polyurethane phase-change materials via a Diels–Alder (DA) reaction. Sunlight irradiation experiments revealed that f-PDAPs addition significantly improved the storage efficiency and photo-thermal conversion of DPCM-x thanks to the superior solar-to-thermal energy conversion performance of the f-PDAPs. Additionally, the existence of both reversible DA networks and f-PDAPs ensured that DPCM-x composites had excellent near-infrared- (NIR-) induced self-healing abilities, thermal-induced recyclable properties and solid-state plasticity. Meanwhile, the recovered DPCM-x composites could largely maintain their original mechanical properties (90.1%) and thermal energy storage capacity. Such cross-linked polyurethane PCM composites exhibited excellent self-healing properties under NIR irradiation. Due to their outstanding recyclability, interesting energy storage ability and form stability, they have enormous potential for applications in the fields of solar-to-thermal energy conversion and storage.
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•Polyethyleneimine functionalized chitosan aerogel is prepared via a facile pathway.•PCA-3 possesses 3D network structure and reversible compressibility.•PCA-3 has superior adsorption ...ability to Cr(VI) with maximum capacity of 445.3 mg/g.•PCA-3 can filter 7.4 L of real Cr wastewater with a concentration of 52.88 mg L−1.•PCA-3 can reduce the accumulation of Cr(VI) in wheat roots and leaves.
Here we unveiled a novel polyethyleneimine (PEI) functionalized chitosan (CS) aerogel (PCA) with three-dimensional (3D) porous network structure and superior reversible compression property and investigated its adsorption behavior toward Cr(VI). The kinetic study displayed that the adsorption of Cr(VI) ions followed the pseudo-second-order model, indicating the adsorption was such as to depend on the chemical reaction between Cr(VI) ions and PCA. Notably, the maximum adsorption capacity fitted according to the Langmuir model was 445.29 mg/g, exceeding those of most previous chitosan-based adsorbents. The major reaction mechanism involving the capture and reduction of Cr(VI) has been systematically investigated based on FTIR, XPS and DFT analyses. Particularly, the fixed-bed column experiments illustrated that the effective treatment volume of PCA was 36367 mL and 7453 mL in simulated chromium wastewater and real chromium wastewater with initial concentrations of 2 mg L−1 and 52.88 mg L−1, respectively, suggesting the promising potential of PCA for large-scale practical applications. More interestingly, the current aerogel adsorbents could significantly reduce the accumulation of heavy metal ions in wheats, which meant that heavy metal wastewater had great prospects for agricultural irrigation after being treated by the aerogel of this work. In summary, this strategy could provide valuable and promising contribution towards the development of scalable and sustainable chitosan-based aerogels for Cr(VI) removal from practical wastewater.
•Over a billions used membrane modules have been discarded as waste into environment.•Here, efficient green route of upcycling discarded synthetic membranes has been explored.•Here, upcycling waste ...from used vast resource resulted in useful functional carbon material.•Carbonaceous materials were used in water remediation and energy storage devices.•Upcycled materials have been repeatedly used in both water treatment and coin-cell devices.
Polymer membranes waste management across the globe is a great concern due to the lack of advancement in upcycling methods. Herein, waste polysulfone (W-PSF) membranes, an emerging environment threat, have been converted to multi-functional carbon materials via green method using choline chloride:FeCl3 (CC:FeCl3) based deep eutectic solvent (DES) systems through solvothermal reaction followed by pyrolysis at 900 °C. The optimized material (Fe-WPSF-01) showed excellent adsorption capacity towards Malachite green (MG), Congo red (CR), Amoxicillin (Amo), and Bisphenol-A (BPA) with 515, 407, 216, and 322 mg/g of adsorption capacity, as calculated from the well-fitted Langmuir isotherm. Further, an easy-to-use adsorptive membrane filtration method was established to investigate the robustness of Fe-WPSF-01 in removing the above pollutants in continuous flow method. The resultant flux rate was 700–815 L.m−2.h−1 with rejection rates of 99, 98, 92, & 98 % for MG, CR, Amo, & BPA, respectively. Besides, the material showed recyclability for up to 10 cycles with 92.1 & 81.2 % of rejection rates for MG and Amo. After the potential usage of carbon material in adsorption studies, secondary materials were again pyrolyzed to use as an electrode in supercapacitors with a specific capacitance of 215 F/g at a current density of 0.1 A/g. Electrode showed capacity retention of 97.51 % even after about 20,000 cycles at an increased current density of about 5 A/g. Thus, a potential sustainable approach of upcycling the W-PSF membranes for energy and environmental applications are well-presented in this work.
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•The as-prepared photocatalyst is obtained by photopolymerization and imprinting technique.•Surface imprinted layer greatly improves the selectivity for TC orientation ...degradation.•Surface imprinted layer inhibits the secondary pollution caused by CdS photocorrosion.•The heterojunction structure formed by PPy and CdS improves the photocatalytic activity.•The introduction of MFA improves the recyclability and achieves the aim of waste treatment.
Environment-friendly MFA-based heterojunction imprinted photocatalyst (PPy@CdS@MFA imprinted photocatalyst) was synthesized by a simple photopolymerization method and surface imprinting technique. The physical and chemical properties of the PPy@CdS@MFA imprinted photocatalyst had been characterized by XRD, FT-IR, XPS, SEM, UV–vis DRS, BET, VSM, etc. In addition, the degradation rate of tetracycline (77.59%) by the PPy@CdS@MFA imprinted photocatalyst was more than twice that of ciprofloxacin (34.57%) by the PPy@CdS@MFA imprinted photocatalyst, and the coefficient of selectivity (kselectivity) of the PPy@CdS@MFA imprinted photocatalyst relative to CdS, CdS@MFA and non-imprinted photocatalyst were 0.71, 1.79 and 1.69, respectively. With an improved recyclability and selectivity, our work provided a feasibility analysis and exemplificative strategy for efficiently orientation degradation of targets with no secondary pollution.
A novel biobased polyurethane with robust mechanical properties, repairability, reprocessability, and shape memory enabled by dynamic hindered urea bonds is reported.
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•Novel biobased ...polyurethanes bearing hindered urea bonds were synthesized.•The polymers possess self-healing, shape memory, and reprocessable properties.•Reversible solid/liquid transformation occurred under cooling and heating treatment.•The polymers can be used as recoverable adhesives and conductive composites.
Developing biobased polyurethanes with repairability, reprocessability as well as robust mechanical properties remains a great challenge. Herein, novel, robust biobased polyurethane materials bearing hindered urea bonds (HUBs) derived from renewable castor oil are reported. The dynamic HUBs and hydrogen bonds that existed in HUBs provided these materials extremely low relaxation times (12.3 to 221 s at 100 °C) as well as excellent scratch healing efficiency (88.9–100% at 100 °C for 10 min) and recyclability (without obviously sacrificing the tensile properties at least 4 times). The selected sample also exhibited good shape memory behavior, with a shape fixity ratio above 88.4% and a shape recovery ratio above 81.3%. Remarkably, the polymers could undergo a rapid and reversible solid/liquid transformation under cooling and heating treatment. Besides, these HUBs materials demonstrated high adhesion strength (up to 2.53 MPa) when bonding stainless steel, and can be re-used for at least 5 times without significant deterioration in adhesion strength. Finally, by mixing a certain amount of carbon nanotubes (CNTs) and adjusting the compositions of HUBs, recyclable and malleable conductive composites were achieved. In general, this work presents a green, simple, and universal approach to fabricate robust, sustainable polyurethanes with multiple functions like repairability, shape memory, malleability, and recyclability.
Metal nanoparticles have drawn great attention in heterogeneous catalysis. One challenge is that they are easily deactivated by migration-coalescence during the catalysis process because of their ...high surface energy. With the rapid development of nanoscience, encapsulating metal nanoparticles in nanoshells or nanopores becomes one of the most promising strategies to overcome the stability issue of the metal nanoparticles. Besides, the activity and selectivity could be simultaneously enhanced by taking advantage of the synergy between the metal nanoparticles and the encapsulating materials as well as the molecular sieving property of the encapsulating materials. In this review, we provide a comprehensive summary of the recent progress in the synthesis and catalytic properties of the encapsulated metal nanoparticles. This review begins with an introduction to the synthetic strategies for encapsulating metal nanoparticles with different architectures developed to date, including their encapsulation in nanoshells of inorganic oxides and carbon, porous materials (zeolites, metal–organic frameworks, and covalent organic frameworks), and organic capsules (dendrimers and organic cages). The advantages of the encapsulated metal nanoparticles are then discussed, such as enhanced stability and recyclability, improved selectivity, strong metal–support interactions, and the capability of enabling tandem catalysis, followed by the introduction of some representative applications of the encapsulated metal nanoparticles in thermo-, photo-, and electrocatalysis. At the end of this review, we discuss the remaining challenges associated with the encapsulated metal nanoparticles and provide our perspectives on the future development of the field.
Magnetically Driven Micro and Nanorobots Zhou, Huaijuan; Mayorga-Martinez, Carmen C; Pané, Salvador ...
Chemical reviews,
04/2021, Volume:
121, Issue:
8
Journal Article
Peer reviewed
Open access
Manipulation and navigation of micro and nanoswimmers in different fluid environments can be achieved by chemicals, external fields, or even motile cells. Many researchers have selected magnetic ...fields as the active external actuation source based on the advantageous features of this actuation strategy such as remote and spatiotemporal control, fuel-free, high degree of reconfigurability, programmability, recyclability, and versatility. This review introduces fundamental concepts and advantages of magnetic micro/nanorobots (termed here as “MagRobots”) as well as basic knowledge of magnetic fields and magnetic materials, setups for magnetic manipulation, magnetic field configurations, and symmetry-breaking strategies for effective movement. These concepts are discussed to describe the interactions between micro/nanorobots and magnetic fields. Actuation mechanisms of flagella-inspired MagRobots (i.e., corkscrew-like motion and traveling-wave locomotion/ciliary stroke motion) and surface walkers (i.e., surface-assisted motion), applications of magnetic fields in other propulsion approaches, and magnetic stimulation of micro/nanorobots beyond motion are provided followed by fabrication techniques for (quasi-)spherical, helical, flexible, wire-like, and biohybrid MagRobots. Applications of MagRobots in targeted drug/gene delivery, cell manipulation, minimally invasive surgery, biopsy, biofilm disruption/eradication, imaging-guided delivery/therapy/surgery, pollution removal for environmental remediation, and (bio)sensing are also reviewed. Finally, current challenges and future perspectives for the development of magnetically powered miniaturized motors are discussed.
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