Switchable catalysis from monomer mixtures has been emerging as a powerful technique to synthesize various useful block copolymers, yet represents a significant challenge in polymer chemistry. Herein, we present the s...
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Switchable catalysis from monomer mixtures has been emerging as a powerful technique to synthesize various useful block copolymers, yet represents a significant challenge in polymer chemistry. Herein, we present the synthesis of well-defined polyacetal/polycarbonate block copolymers through switchable polymerization from mixtures of terminal epoxides, internal epoxides, o -phthalaldehyde (OPA) and CO 2 . The exclusive chemoselectivity of terminal epoxide or internal epoxide was achieved by controlling the reaction atmosphere. The dynamic equilibrium of acetal anion and alkoxy anion is the key to the successful switch from terminal epoxides/OPA copolymerization to internal epoxides/CO 2 copolymerization. Computational studies elucidated the kinetic and thermodynamic preferences underlying this selective polymerization. The acid/base labile nature of the block copolymers enables their sequence-controlled chemical recycling/degradation. These novel polyacetal/polycarbonate block copolymers with facilely sequence-controlled polymerization/depolymerization capabilities will enable their further tailored applications and contribute to the development of a circular plastic economy.
A combined method of electrostatic adsorption and green reduction was successfully employed to synthesize graphene-loaded carbon nanofibers (G/CNFs). The graphene nanoflakes enhanced the degree of graphitization of CN...
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Introduction: The objective of this work was to fabricate a novel class of protein carriers from double-bond-functionalized multiarm poly(ε- caprolactone) maleic acid (PGCLM) microspheres and to examine protein susta...
Introduction: The objective of this work was to fabricate a novel class of protein carriers from double-bond-functionalized multiarm poly(ε- caprolactone) maleic acid (PGCLM) microspheres and to examine protein sustained-release profiles in vitro over a period of a few months. Methods: The double-emulsion technique was used to formulate terminal functionalized three-arm PGCLM microspheres having three different types of functional groups (-OH, -COOH, and -C = C-), and one of the functional groups (>C = < bonds) was used to formulate surface-crosslinked microspheres (NPGCLM). Ovalbumin (OVA) was used as a model protein for examining its release profiles from PGCLM and NPGCLM microspheres in 0.1M phosphate-buffered saline (PBS) at 37°C. These microspheres were also characterized in terms of their morphology, size distribution, and stability. Results: The mean size of fabricated microspheres ranged from 21.9μm to 51.1μm. An OVA protein was successfully encapsulated into these biodegradable PGCLM microspheres with loading efficiency ranging from 34.2% to 46% (w/w), depending on the ratio of PGCLM to polyvinyl alcohol (PVA) stabilizer. Depending on the polymer to PVA stabilizer ratio, the cumulative OVA release % (w/w) in 0.1M PBS at 37°C ranged from 30% to 40% within 50 days. We further demonstrated the availability of the functional >C = C< bonds on the surface of PGCLM microspheres, which we expect could be used for either covalent binding of bioactive agents or imparting different chemical characteristics onto the surface of the microspheres for broadening of their applications. Discussion/Conclusion: A method for the preparation of biodegradable microspheres from water/oil emulsion of multiarm and functionalized poly(ε-caprolactone) [PGCL, PGCLM, and NPGCLM] was reported as a potential means of developing injectable therapeutic formulations for drugs. The most unique aspect of these biodegradable microspheres is the availability of two functional groups (>C = C< bon
The development of advanced bifunctional oxygen electrocatalysts for oxygen reduction and evolution reactions(ORR and OER) is critical to the practical application of zinc-air batteries(ZABs). Herein, a silica-assiste...
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The development of advanced bifunctional oxygen electrocatalysts for oxygen reduction and evolution reactions(ORR and OER) is critical to the practical application of zinc-air batteries(ZABs). Herein, a silica-assisted method is reported to integrate numerous accessible edge Fe-Nx sites into porous graphitic carbon(named Fe-N-G) for achieving highly active and robust oxygen electrocatalysis. Silica facilitates the formation of edge Fe-Nx sites and dense graphitic domains in carbon by inhibiting iron *** purification process creates a well-developed mass transfer channel for Fe-N-G. Consequently,Fe-N-G delivers a half-wave potential of 0.859 V in ORR and an overpotential of 344 m V at10 m A cm^(-2)in OER. During long-term operation, the graphitic layers protect edge Fe-Nx sites from demetallation in ORR and synergize with Fe OOH species endowing Fe-N-G with enhanced OER *** functional theory calculations reveal that the edge Fe-Nx site is superior to the in-plane Fe-Nx site in terms of OH* dissociation in ORR and OOH* formation in OER. The constructed ZAB based on Fe-N-G cathode shows a higher peak power density of 133 m W cm^(-2)and more stable cycling performance than Pt/C + RuO2counterparts. This work provides a novel strategy to obtain high-efficiency bifunctional oxygen electrocatalysts through space mediation.
The lithium aluminum titanium phosphate (LATP)/Polyacrylonitrile (PAN) composite fiber-based membrane were prepared by electrospinning composite solution of LATP and PAN in N, N-dimethylformamide(DMF). The crystalliza...
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ISBN:
(纸本)9787122120199
The lithium aluminum titanium phosphate (LATP)/Polyacrylonitrile (PAN) composite fiber-based membrane were prepared by electrospinning composite solution of LATP and PAN in N, N-dimethylformamide(DMF). The crystallization phase of the LATP particles were characterized by X-ray diffraction(XRD). The electrolyte uptakes of the electrospun LATP/PAN composite fiber-based membranes were also evaluated. In addition, the electrochemical performance of the liquid electrolyte-soaked electrospun LATP/PAN composite fiber-based is also improved after the introduction of LATP particles.
作者:
Shu ZhangYing LiGuanjie XuShuli LiYao LuOzan ToprackiXiangwu ZhangFiber and Polymer Science Program
Department of Textile Engineering Chemistry and Science North Carolina State University Raleigh NC..Fiber and Polymer Science Program Department of Textile Engineering Chemistry and Science North Carolina State University Raleigh NC..Fiber and Polymer Science Program Department of Textile Engineering Chemistry and Science North Carolina State University Raleigh NC..Fiber and Polymer Science Program Department of Textile Engineering Chemistry and Science North Carolina State University Raleigh NC..Fiber and Polymer Science Program Department of Textile Engineering Chemistry and Science North Carolina State University Raleigh NC..Fiber and Polymer Science Program Department of Textile Engineering Chemistry and Science North Carolina State University Raleigh NC..Fiber and Polymer Science Program Department of Textile Engineering Chemistry and Science North Carolina State University Raleigh NC..
Li2MnSiO4 has an extremely high theoretical capacity of 332 mAh?g?1. However, only around half of this capacity has been realized in practice and the capacity retention during cycling is also low. In this study, Li2Mn...
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Li2MnSiO4 has an extremely high theoretical capacity of 332 mAh?g?1. However, only around half of this capacity has been realized in practice and the capacity retention during cycling is also low. In this study, Li2MnSiO4/carbon composite nanofibers were prepared by a combination of electrospinning and heat treatment. The one-dimensional continuous carbon nanofiber matrix serves as long-distance conductive pathways for both electrons and ions. The composite nanofiber structure avoids the aggregation of Li2MnSiO4 particles, which in turn enhances the electrode conductivity and promotes the reaction kinetics. The resultant Li2MnSiO4/carbon composite nanofibers were used as the cathode material for Li-ion batteries, and they delivered high charge and discharge capacities of 218 and 185 mAh?g?1, respectively, at the second cycle. In addition, the capacity retention of Li2MnSiO4 at the first 20th cycles increased from 37% to 54% in composite nanofibers.
Janus electrospinning nanofiber membranes have attracted extensive attention in the fields such as solar-driven interfacial desalination,liquid filtration,and waterproof and breathable ***,the Janus structures suffer ...
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Janus electrospinning nanofiber membranes have attracted extensive attention in the fields such as solar-driven interfacial desalination,liquid filtration,and waterproof and breathable ***,the Janus structures suffer from weak interfacial bonding and vulnerability to damage,making the durability and sustainability are highly sought after in real-word ***,we fabricate the simply reconfigurable and entirely self-healing Janus evaporator by electrospinning polypropylene glycol based polyurethane(PPG@PU)and polydimethylsiloxane based polyurethane-CNTs(PDMS@PU-CNTs)with different wettability,which are both designed based on dynamic Diels–Alder(DA)*** interface of the Janus membrane is stitched by the covalent bonds to directly improve the interface adhesion to 22 N·m−1,constructing an integrated evaporator,and thereby achieving a stable desalination rate of 1.34 kg·m−2·h−1 under one *** dissociation of DA networks allows the evaporators for self-healing and reconfiguration abilities,after which the photothermal performance is *** is the first work for the crosslinked self-healing polymer to be directly electrospun,achieving the improved interfacial bond and reconfiguration of entire evaporators,which presented promising new design principles and materials for interfacial solar seawater desalination.
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