Search

Polycaprolactone with azide (PCL-N3) and polyethylene glycol with α,β-unsaturated ester (maPEG) as chain-end functional group were synthesized, respectively. Then, facile synthesis of polycaprolactone-block-polyethylene glycol (PCL-b-PEG) amphiphilic copolymer by azide-zwitterion cycloaddition of PCL-N3and maPEG, as the first example, was reported. The self-assembly of this amphiphilic copolymer was carried out in deionized water, and then the formation of vesicles was proven by the result of transmission electron microscope (TEM). Grainsize analyzer suggested that the diameter of the vesicles is 305 nm in average and the polydispersity of the vesicles is 0.128. The azide-zwitterion cycloaddition provides a powerful method for the post-functionalization of α,β-unsaturated ester or azide end-functionalized polymers. [ABSTRACT FROM AUTHOR]

Ring-opening Copolymerization of Epoxides and Cyclic Anhydrides catalyzed by UiO MOFs. [Display omitted] • The ROCOP of epoxides and cyclic anhydrides was succesfully carried out caltalyzed by UiO MOFs. • Polyesters with a wide range of monomer adaptability were synthesized. • The kinetic study showed that ROCOP of epoxide with cyclic anhydride catalyzed by UiO-67 was a first-order kinetic reaction. • The UiO-67 has good recoverability and without loss of catalytic activity after been reused. Ring-opening copolymerization (ROCOP) of epoxide with cyclic anhydride plays critical role in the preparation of polyesters. Herein, the UiO-type MOFs including UiO-66, UiO-66-NH 2 , UiO-66-NO 2 , UiO-66-Br and UiO-67 with octahedral morphology were synthesized by different ligands and used as heterogeneous catalysts for ROCOP of epoxide with cyclic anhydride. It was shown that the UiO-67 with ultra-high specific surface area and large pore size endows it with abundant of catalytic active sites and the highest catalytic activity, which makes UiO-67 present seven times higher turnover frequency (192.6 h−1) than that of UiO-66 (23.6 h−1) under the same conditions. Besides, the strong electron-absorbing group enhances the catalytic activity of UiO-type MOFs. The cycling test proves that the UiO-67 has good recoverability and there was no significant loss of catalytic activity after been reused for three times. The kinetic study showed that the ROCOP of epoxide with cyclic anhydride catalyzed by UiO-67 was a first-order kinetic reaction, and its apparent activation energy (E a) was about 71.75 kJ∙mol−1 calculated by the Arrhenius equation, which was 27.5% lower than that of UiO-66 (98.94 kJ∙mol−1). [ABSTRACT FROM AUTHOR]

Achieving a balance between flame retardancy and overall performance in epoxy resin (EP) continues to be a significant challenge. In this study, a new multi-DOPO-based reactive flame retardant (DZH) was synthesized successfully using a simple one-pot method and employed as a co-curing agent with DDM. The results indicated that the inclusion of DZH decreased the activation energy of the curing reaction system. Furthermore, the presence of DZH, with its remarkable charring ability, enhanced the formation of char residues under high-temperature conditions. Notably, the flame retardancy and mechanical properties of the EP/DZH system were significantly enhanced at certain additions. When added at only 5 wt% (phosphorus content: 0.525 wt%), the LOI value of the EP/DZH-5 increased from 24.4 % to 35.3 % for the EP matrix and achieved a V-0 rating in accordance with UL-94. Meanwhile, EP/DZH-5 exhibited a reduction of 44.1 % in pHRR and 24.3 % in SPR. The superior flame retardancy of the EP/DZH system was attributed to the dual flame-retardant mechanism exhibited in both the gaseous and condensed phases. In addition, the abundant presence of rigid phosphaphenanthrene groups and π-π interactions between benzene rings led to an improvement in the tensile strength and tensile modulus, which rose to 91.0 MPa and 1.76 GPa, respectively, from 79.5 MPa and 1.26 GPa of EP in the case of EP/DZH-3. The utilization of this flame retardant, based on multi-DOPO, offers a promising approach for the development of high-performance epoxy resins. [Display omitted] • A one-pot method successfully synthesized a flame retardant with ample aromatic and reactive functional groups. • DZH accelerated the cross-linking reaction of EP system. • A low addition amount of DZH provided excellent flame retardancy and mechanical properties. • The biphasic flame-retardant mechanism of DZH was revealed in detail. [ABSTRACT FROM AUTHOR]

Although transition metal hydroxides/sulfides are considered as promising potential electrode materials for supercapacitors due to their excellent electrochemical activity, the low electrical conductivity, easy agglomeration of nanomaterials and poor rate performance seriously hinder their practical applications. Herein, we construct 3D interconnected binder-free electrode NiCo 2 S 4 /bio-carbon coated nickel foam (NiCo 2 S 4 /GRCNF) by growing NiCo 2 S 4 nanosheets on the surface of low-cost and highly conductive GRCNF substrate via a simple hydrothermal reaction followed with subsequent sulfidation. As suggested by systematic characterizations, the advantages of obtained NiCo 2 S 4 /GRCNF include that the ultrathin 3D interconnected network of NiCo 2 S 4 can furnish massive electrochemically active sites for faradic reaction, and the highly conductive GRCNF substrate promotes electron transfer and meanwhile prevents the aggregation of NiCo 2 S 4 nanosheets. With a high specific capacitance of 7.71 F cm−2 at 3 mA cm−2, NiCo 2 S 4 /GRCNF has a huge application advantage over the contrast samples Ni-Co LDH/NF (3.29 F cm−2) and Ni-Co LDH/GRCNF (5.97 F cm−2). In addition, NiCo 2 S 4 /GRCNF shows a much higher rate performance (82.1%) than Ni-Co LDH/NF (44.5%) and Ni-Co LDH/GRCNF (66.4%). Furthermore, hybrid supercapacitor NiCo 2 S 4 /GRCNF//GNPC which is assembled with NiCo 2 S 4 /GRCNF as the anode possesses an impressive energy density of 0.429 mWh cm−2 at a power density of 7.023 mW cm−2 and good cycling stability (82.3% over 5000 cycles). The outstanding electrochemical performance of NiCo 2 S 4 /GRCNF suggests that the reported strategy provides new inspiration for the design and preparation of new binder-free composite electrodes for electrochemical energy storage. [Display omitted] • 3D interconnected NiCo 2 S 4 /GRCNF composites were synthesized for binder-free electrode materials. • Glutinous rice flour contains more amylopectin which can provide higher stickiness during gelatinization. • The GRC biomass carbon layer on the surface of NF enhances the electrical conductivity of the skeleton. • NiCo 2 S 4 /GRCNF exhibits excellent specific capacitance of 7.71 F cm−2 at 3 mA cm−2. [ABSTRACT FROM AUTHOR]

The photo-induced reversible complexation-mediated radical polymerization (photo-induced RCMP) has the feature of energy-saving and environmentally friendly, which is compatible with the sustainable development advocated by the world. To promote the development of photo-induced RCMP, three two-dimensional conjugated microporous polymers (CMPs) based on different construction units were developed by aldehyde-ammonia condensation and used as catalysts, producing polymethacrylates with precise molecular weight and narrow molecular weight dispersion. Chain extension, monomer compatibility and spatiotemporal control experiments revealed the high chain end fidelity of obtain polymethacrylates and the universality of photo-RCMP process by using synthetic CMPs catalysts. The density functional theory (DFT) calculation reveals that all the highest unoccupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of three CMPs are in junction segment and connecting segment respectively, which exhibits strong electron distribution asymmetry. Moreover, the DFT and experimental results verified that the (donor-acceptor) D-A structure with push-pull electron ability and π-conjugated electron channel promote intermolecular charge transfer, which reduce the Gibbs free energy of photo-induced RCMP to increase the electron transport ability and the polymerization rate. This work indicates that by the construction of D-A structure and π-conjugated electron channel can effectively enhance the catalytic properties of CMPs-based photocatalysts, which provides a methodology to design heterogeneous photocatalysts for photo-induced RCMP. [Display omitted] • Three CMPs heterogeneous photo-catalysts were prepared by aldehyde-ammonia condensation. • D-A and higher degree of π-conjugation reduces the activation energy barrier of the initiator and raises photo-induced RCMP. • D-A structure and higher degree of π-conjugation played critical role to CMPs enhance catalytic performance. [ABSTRACT FROM AUTHOR]

In this work, a series of N-doped porous carbons (NPCs) are prepared via high internal phase emulsion (HIPE) template, followed by growing polyaniline (PANI) arrays and subsequent carbonization/activation. As evidenced by SEM and N 2 absorption/desorption results, the NPCs have interconnected hierarchical porous structures with abundant micropores and mesopores inside. The morphology and porous structures of NPCs can be tuned by changing aniline concentration and polymerization time, respectively. With the increase of aniline concentration or polymerization time, the porous structure of NPC becomes more and more serried, however too high aniline concentration (>0.75 M) makes the porous structure become sparse, which is because excess PANI will nucleate itself and make it detach from the surface of NPC. As a result, the specific surface area (SSA) of NPCs first increases to 1769 m2/g and then decreases. Electrochemical performances of the obtained NPCs are evaluated in detail. The test results indicate that both aniline concentration and polymerization time have notable influence on the specific capacitance of NPCs. The specific capacitance of NPC obtained under optimized conditions reaches up to 241 F/g at 1 A/g with a retention ratio of 97.8% after 10, 000 cycles at a high current density, proving its excellent energy storage capability and cycling stability. In two-electrode system, the NPC provides an energy density of 27 Wh/kg at a power density of 400 W/kg and remains a high energy density of 19 Wh/kg at a high power density of 10002 W/kg. [Display omitted] • N-doped porous carbons are prepared from polymer/polyaniline array composites. • N-doped porous carbons have hierarchical porous structures with high surface area. • N-doped porous carbons have high specific capacitance up to 241 F/g at 1A/g. • N-doped porous carbons show a retention ratio of 97.8% after 10, 000 cycles. • N-doped porous carbons maintain high energy density in wide power density range. [ABSTRACT FROM AUTHOR]

Inspired by the biological tissues that can autonomously grow with respect to the surrounding mechanical environment, a dual-responsive hydrogel actuator was well developed by integrating such the characteristics as self-strengthening, strain-adaptive stiffening, and intelligent actuation into the single device. [Display omitted] • A dynamically adaptive bilayer hydrogel actuator of PVA/PNIPAm was developed. • In the bilayer hydrogel actuator, each monolayer functions differently. • This actuator can perform rapid 3D actuation upon temperature/salt stimuli. • This bio-inspired hydrogel actuator can display the self-strengthening behavior. Inspired by intelligent biomaterials which often have flexible responsiveness to multiple environmental cues and strengthen their mechanical properties by trainings, emerging soft actuators require programmable manipulation. Currently, the integration of such characteristics as rapid self-strengthening, strain-adaptive stiffening and smart actuation, into a single hydrogel actuator is urgently needed. Here, we report a self-strengthened hydrogel actuator based on the semi-interpenetrating polymer network consisting of polyvinyl alcohol (PVA) and poly(N-isopropylacrylamide) (PNIPAm), which can display diverse programmable actuations by responding to temperature/salt stimuli. In the design, the layer of freeze-thawed PNIPAm/PVA (PPGel-F) is assembled with another original PNIPAm/PVA hydrogel layer (PPGel) into one device. By taking advantage of the PVA crystalline nanofibrils in the PPGel-F matrix, the differentiated swelling degree across the bilayer structure gives rise to asymmetric deformations and the resultant shape transformation. Moreover, upon the mechanical training with less than 100 cycles, the anisotropic arrangement of PVA nanofibrils through strong hydrogen bonding interactions can swiftly immobilize the amorphous polymer chains orientation along the tensile direction. This enhances the strain-induced crystallization, thereby generating the rapid self- strengthening behavior. The proposed work provides potential solution for constructing dynamically adaptive hydrogel systems that can mimic biological tissues for more intelligent soft robotics and bionic research. [ABSTRACT FROM AUTHOR]

Electronic-grade isopropyl alcohol is widely utilized in the cleaning of semiconductors and microelectronic components. Removing ions like Pb 2+ is crucial since the presence of impurities may cause degradation of electronics, increased failure rates, and short circuits. Membrane materials offer a number of advantages in the field of adsorption separation; however, the lack of adsorption sites results in limited adsorption capacity. In the current work, guanidino-grafted NH 2 -MIL-101(Fe) was incorporated into polyvinylidene fluoride (PVDF) to prepare MOF/PVDF mixed matrix membranes (NM/PVDF) for the removal of Pb 2+ from isopropanol. Benefiting from the larger specific surface area and more lone electron pairs in the guanidine group, the Pb 2+ adsorption capacity of the as-prepared NM/PVDF membrane was 29.4458 mg/g, which was higher than that of the NH 2 -MIL-101(Fe)/PVDF membrane (20.9306 mg/g) and the pure PVDF membrane (6.7324 mg/g). The NM/PVDF membrane was able to reduce the concentration of Pb 2+ from 500 to 86.73 ppb. This work highlights the potential of guanidine-grafted Fe-based MOFs/PVDF membranes as adsorbents for acquisition of electronic-grade solvents.

Recovery and separation of anthropogenic emissions of electronic specialty gases (F-gases, such as CF 4 and SF 6 ) from the semiconductor sector are of critical importance. In this work, the hierarchical porous UiO-66-Br 2 @PS/DVB-packed column was constructed by a high internal phase emulsions strategy. UiO-66-Br 2 @PS/DVB exhibits a superior selectivity of CF 4 /N 2 (2.67) and SF 6 /N 2 (3.34) predicted by the IAST due to the diffusion limitation in the micropore and the gas-framework affinity. Especially, UiO-66-Br 2 @PS/DVB showed significant CF 4 and SF 6 retention and enabled the successful separation of CF 4 /N 2 and SF 6 /N 2 with a resolution of 2.37 and 8.89, respectively, when used as a packed column in gas chromatography. Compared with the Porapak Q column, the HETP of the UiO-66-Br 2 @PS/DVB-packed column decreased and showed good reproducibility. This research not only offers a convenient method for fabricating a hierarchical porous MOF-packed column but also showcases the prospective utilization of MOFs for the separation of the F-gas/N 2 mixture.

Removal of hetero ions from the hydrogen peroxide solution is a crucial step in purifying electronic-grade H 2 O 2 . Conventional adsorption materials are challenged to meet the need for the simultaneous adsorption of both anions and cations in solvents. UiO-66 (Zr) modified by acetic acid and amino group for simultaneous adsorption of phosphate and Pb 2+ in H 2 O 2 purification was fabricated in this work. The as-prepared defective UiO-66-NH 2 (Zr) demonstrated a significant increase in specific surface area and porosity, along with more exposed sites for phosphate and Pb 2+ adsorption. The adsorption capacity of De-UiO-66-NH 2 for phosphate and Pb 2+ in H 2 O 2 solution was 52.28 mg g -1 and 35.4 mg g -1 , which is 1.19 times and 1.88 times that of unmodified UiO-66 (Zr), respectively. The trace simultaneous adsorption with both 100 ppb phosphate and Pb 2+ showed removal rates of 94.0% and 88.7%, respectively, confirming the practicality of MOF materials in the purification of electronic chemicals. This work highlights the potential of Zr-based MOFs as anionic and cationic simultaneous adsorbents for highly efficient purification of electronic-grade solvents.

The conversion of CO 2 into value-added chemicals has become an imminent research topic and the cycloaddition of CO 2 with a C1 resource to produce cyclic carbonates is a promising pathway for CO 2 utilization. Herein, a series of POSS-based polyionic liquids (PILs) were synthesized by the copolymerization of octavinyl polyhedral oligomeric silsesquioxane (POSS) with an imidazolium ion linker. The prepared PILs have the characteristics of hydrogen bond donors, halogen atom sites, stable pore structures, and thermal stability, and are used as heterogeneous catalysts for the cycloaddition of epoxides with carbon dioxide. The effect of linkers on the cycloaddition is investigated by tuning the ratio of POSS units to imidazolium ions. Under the optimized conditions, the conversion of epichlorohydrin can reach 99.18% at atmospheric pressure with neither co-catalysts nor solvents. It is concluded that the reaction of the cycloaddition of epoxides with carbon dioxide follows pseudo-first-order kinetics. Moreover, the presence of the catalysis of PILs leads to a significant decrease in the activation energy barrier for cycloaddition. The catalyst can be facilely recovered due to its high stability, and only a slight decrease in conversion was observed after five successive runs. In addition, the mechanism of PILs catalyzing the cycloaddition reaction of epoxides with CO 2 is proposed. This work not only provides a sustainable and green process for CO 2 cycloaddition, but also highlights the potential of using PILs for CO 2 utilization.

CoS x materials with high catalytic activity are considered as promising HER electrocatalysts, but their inherent low electrical conductivity and easy loss of active sites have greatly limited their applications in OER electrocatalysis. Herein, we present a convenient method to synthesize Co-Cu hollow nanoprisms after wrapping and calcining with trithiocyanuric acid (C 3 H 3 N 3 S 3 ) (denoted N-Co-Cu-S-x HNs). The results showed that Cu doping modified the charge density of Co center, leading to the enhancement of the intrinsic activity of the Co 3 S 4 active center, meanwhile wrapping trithiocyanuric acid on the surfaces and calcinating to form N-containing C skeleton as a flexible substrate to encapsulate the catalysts, which effectively protected the active sites inside the catalysts. Notably, the OER catalyst that was optimized by adjusting the metal ratio and controlling the trithiocyanuric acid incorporation exhibited a low overpotential of 306 mV under a current density of 10 mA cm -2 and showed a superior durability of more than 27 h. This work may provide some insights into the preparation of oxygen evolution reaction catalysts with excellent performance through doping transition metals and protecting the internal active sites strategies., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Chitosan hydrogel microspheres derived from the LiOH/KOH/urea aqueous system demonstrate great characteristics of high mechanical strength, relative chemical inertness, renewability and 3-D fibrous network, making them promising functional supports. This work aims to investigate the tunable Co 2+ adsorption behaviors on these robust chitosan microspheres in detail, providing the theoretical basis for optimizing the preparation procedure of chitosan microspheres supported Co 3 O 4 catalysts in the future. The experimental results revealed that the fabricated original chitosan microspheres with more extended chain conformation could display enhanced adsorption capacity for Co 2+ at determined concentration both in water and alcohol solutions, which is about 2-7 times higher than that of the conventional chitosan hydrogel microspheres prepared from the acetic acid solution. The kinetic experiments indicated that the adsorption process in water solution agreed with the pseudo-second-order kinetic equation mostly, while the chemical and physical adsorptions commonly contribute to the higher Co 2+ adsorption on chitosan microspheres in alcohol solution. Moreover, in both cases, the film diffusion or chemical reaction is the rate limiting process in the initial adsorption stage, and the adsorption of Co 2+ on chitosan microspheres can well fit to the Langmuir isotherm. Thermodynamic analysis demonstrated that such adsorption behaviors were dominated by an endothermic (Δ H ° > 0) and spontaneous (Δ G ° < 0) process., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Lipophilic 6-O-poly (ϵ-caprolactone)-L-ascorbic acid (AA-6-PCL) is synthesized through ROP of ϵ-caprolactone (CL). The number of repeating CL units in the polymer chain varies from 6 to 19. AA-6-PCL loaded supramolecular polymer micelles (SMPMs) are constructed with β-cyclodextrin (β-CD) and PCL as blocks. Transmission electron microscopy images show a nanospheric morphology of the micelles with a size range of 43.3 ± 5.0 nm. The drug loading contents are 22.53-39.23% for AA-6-PCL. AA-6-PCL exhibits high radical scavenging capacity (93.96-96.73%) and efficient scavenging potency, and a cytotoxicity study proves the excellent cytocompatibility of AA-6-PCL loaded β-CD/PCL SMPMs, which altogether herald their potential application in the study of the induced pluripotent stem cells., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)