Nitrogen-doped hierarchical porous carbon nanospheres (NHPCNs) with mesoscale and microscale pores are reported herein for their application in high-performance supercapacitor electrode materials (SCMs). The NHPCNs were facilely prepared via the carbonization of mesoporous polydopamine nanospheres (MPNSs) fabricated by one-step self-polymerization of dopamine using Pluronic F127 as a soft template. The influence of polymerization and carbonation temperatures on the morphologies, structures, and capacitor performances of the as-prepared NHPCNs was investigated systematically. The specific surface area of the NHPCNs can be achieved as high as 1725 m2 g−1, together with a pore volume of 1.85 cm3 g−1. Due to their unique structure, the NHPCNs can act as high-performance SCMs and exhibit high charge storage capacity with a high specific capacitance of 433 F g−1 in 6 M KOH at a current density of 0.5 A g−1 and excellent stability with 95.7% of the initial capacitance after 10 000 cycles.

In this work, we demonstrated a facile green method for the preparation of fluorescent copper nanoclusters (Cu NCs) with a high quantum yield of 8.6%, using glutathione as the stabilizing agent and ascorbic acid as the reductant. The as-prepared Cu NCs had good water solubility and ultrafine sizes. Further investigation revealed that the fluorescence of Cu NCs was linearly quenched by nitrite ions over the concentration range of 10–225 μM, with the detection limit of 3.4 μM. The proposed method has been successfully applied to determine nitrite ions in real water samples.

ABSTRACTThe research activities in the development of recyclable and reprocessable covalently crosslinked networks, and the construction of polymers from renewable resources are both stemmed from the economical and environmental problems associated with traditional thermosets. However, there is little effort in combination of these two attractive strategies in material designs. This article reported a bio-based vitrimer constructed from isosorbide-derived epoxy and aromatic diamines containing disulfide bonds. The resulted dynamic epoxy resins showed comparable thermomechanical properties as compared to similar epoxy networks cured by traditional curing agent. Rheological tests demonstrated the fast stress relaxation of the dynamic network due to the rapid metathesis of disulfide bonds at temperature higher than glass transition temperature. This feature permitted the recycling and reprocessing of the fragmented samples for several times by hot press. The dynamic epoxy resins also exhibited shape-memory effect, and it is demonstrated that the shape recovery ratio could be readily adjusted by controlling the stress relaxation in the temporary state at programming temperature. Moreover, the degradability of the dynamic epoxy resins in alkaline aqueous solution was also demonstrated. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1790–1799

•Disulfide bonds and metal-ligand co-crosslinked network with improved mechanical and self-healing properties.•Polymer network co-crosslinked by disulfide bonds and imidazole-Zn2+ was fabricated.•The incorporation of non-covalent bonds greatly improved the mechanical properties of covalent network.•The fast dynamic exchange of non-covalent bonds improved the self-healing efficiency of covalent network.The simultaneous improvement of mechanical properties and healing efficiency of self-healing polymers is often contradictory because of the different requirements of chain mobility for these two demands. In this study, we have incorporated imidazole-zinc ion coordination bonds into a disulfide based cross-linked network to investigate the influence of non-covalent bonds on the mechanical properties and healing efficiency of dynamic covalent network. It is found that the modulus, strength, and toughness of covalent network were greatly improved by the introduction of non-covalent bonds due to the additional cross-linking and energy dissipation functions of non-covalent bonds. While the time dependent healing test revealed the higher healing efficiency of covalent network by the addition of non-covalent bonds because of their faster exchange dynamics as compared to dynamic covalent bonds. The co-crosslinked network can also be reprocessed by hot press due to the dynamic nature of both covalent and non-covalent crosslinkings.Download high-res image (150KB)Download full-size image

•Poly(ε-caprolactone) were covalently grafted onto polydopamine particles by in-situ polymerization.•The modified polydopamine particles dispersed homogeneously in polymer matrix.•The mechanical properties of composites significantly improved by the incorporation of fillers.•The composites showed near-infrared light response and fast optical healing ability.Polydopamine particles (PDAPs) were used as fillers for construction of multifunctional composites with poly(ε-caprolactone) (PCL) as matrix. To improve the dispersion of PDAPs in matrix and interfacial compatibility in the composites, PCL was firstly grafted onto PDAPs by in-situ ring-opening polymerization of ε-caprolactone. The successful grafting of PCL chains on PDAPs, as evidenced by the FT-IR, elemental analysis, electron microscope and dispersion tests, has greatly improved the dispersion state and interfacial adhesion between hydrophilic PDAPs and hydrophobic PCL, thus resulted in increased degree of crystallinity, and significantly improved modulus and yield strength of PCL. The photothermal effect of PDAPs have also endowed the composites with good photothermal conversion ability. The temperature of composites could rapidly rise up to the melting temperature of polymer upon exposure to near-infrared light, and thus allowed fast optical healing and fully recovered mechanical properties of the composites upon damage based on a melting-recrystallization mechanism.

The assembly of metal nanoparticles (NPs) has attracted a great deal of attention recently because of their collective properties that could not be exhibited by individual NPs. Here a one-step approach was reported for the fabrication of spherical silver NP assemblies (AgNAs). The formation of AgNAs simply included the stirring of silver ammonia and 3,4-dihydroxy-l-phenylalanine (DOPA) in aqueous solution at room temperature, in which DOPA acted as a reductant for AgNPs first because of its reducing ability and then directed the assembly of AgNPs into AgNAs. The AgNAs exhibited hierarchical structure with controllable sizes ranging from 180 to 610 nm by adjusting the concentrations of reagents. The two individual components, AgNPs and polyDOPA, also allowed AgNAs with multiple functions as demonstrated in this study of durable catalytic activity, high SERS sensitivity, and good antioxidant properties. The thin polyDOPA layer coated on AgNAs further offered the opportunity to modify the surface of AgNAs. The results presented here may provide a green and facile approach to designing multifunctional NP assemblies.

To support rapid advancements in the field of biocomposites, it is necessary to exploit novel fillers that are biocompatible, multifunctional and easy to obtain. In this work, polydopamine particles (PDAPs) have been reported as a filler for constructing polymer composites. PDAPs with average diameters of about 1040 and 310 nm were first prepared by a convenient oxidative polymerization of dopamine, then PDAP/poly(vinyl alcohol) (PVA) composites were prepared through a traditional solution-casting method. Measurements on the resultant composites confirmed strong interactions between the PDAPs and PVA chains and the good dispersion of PDAPs throughout the matrix. It was found that the PDAPs could promote the crystallization of PVA and, thus, greatly improve the mechanical properties of the composites. TGA results showed that both the initial and maximum decomposition temperatures of PVA were significantly increased by the addition of PDAPs. Moreover, the composites showed superior antioxidant properties and UV-shielding efficiency compared to neat PVA. The effect of particle size on the reinforcement was also evaluated. The results suggested that PDAPs could be a good candidate for use in multifunctional composites.

•Polybenzimidazole (PBI) functionalized graphene platelets (fGnPs) were fabricated.•The fGnPs were highly integrated and could be well exfoliated in organic solvent.•The grafted PBI chains served as strong interfaces in fGnPs/Epoxy composites.•fGnPs/Epoxy composites showed significantly improved mechanical and thermal properties.This paper reported a facile one-pot strategy for covalent functionalization of graphene platelets (GnPs) by polybenzimidazole, and the fabrication of their composites with epoxy resin. The functionalized GnPs (fGnPs) was prepared by subsequently acylation reaction between dicarboxylic acid and GnPs, and in-situ polymerization of polybenzimidazole. Spectroscopic studies and elemental analysis confirmed the successful grafting of polymer chains and the highly integrated structure of fGnPs, while TEM images demonstrated the well exfoliated state of fGnPs in organic solvent. As a consequence of the good dispersion state of fGnPs in matrix, and the covalent interactions between fGnPs and epoxy, the fGnPs/Epoxy composites showed significantly improved Young's modulus, tensile strength and fracture toughness as compared to neat epoxy or unmodified GnPs reinforced epoxy. The improved dynamic mechanical properties and thermal stabilities of composites filled with fGnPs were also demonstrated.

To support rapid advancements in the field of biocomposites, it is necessary to exploit novel fillers that are biocompatible, multifunctional and easy to obtain. In this work, polydopamine particles (PDAPs) have been reported as a filler for constructing polymer composites. PDAPs with average diameters of about 1040 and 310 nm were first prepared by a convenient oxidative polymerization of dopamine, then PDAP/poly(vinyl alcohol) (PVA) composites were prepared through a traditional solution-casting method. Measurements on the resultant composites confirmed strong interactions between the PDAPs and PVA chains and the good dispersion of PDAPs throughout the matrix. It was found that the PDAPs could promote the crystallization of PVA and, thus, greatly improve the mechanical properties of the composites. TGA results showed that both the initial and maximum decomposition temperatures of PVA were significantly increased by the addition of PDAPs. Moreover, the composites showed superior antioxidant properties and UV-shielding efficiency compared to neat PVA. The effect of particle size on the reinforcement was also evaluated. The results suggested that PDAPs could be a good candidate for use in multifunctional composites.