Three-dimensional (3D) nanostructured conducting polymer hydrogels represent a group of highperformance electrochemical energy-storage materials. Here, we demonstrate a molecular self-assembly approach toward controlled synthesis of nanostructured polypyrrole (PPy) conducting hydrogels, which was "cross-linked" by a conjugated dopant molecule trypan blue (TB) to form a 3D network with controlled morphology. The protonated TB by ion bonding aligns the free sulfonic acid groups into a certain spatial structure. The sulfonic acid group and the PPy chain are arranged by a self-sorting mechanism to form a PPy nanofiber structure by electrostatic interaction and hydrogen bonding. It is found that PPy hydrogels doped with varying dopant concentrations and changing dopant molecules exhibited controllable morphology and tunable electrochemical properties. In addition, the conjugated TB dopants promoted interchain charge transport, resulting in higher electrical conductivity (3.3 S/ cm) and pseudocapacitance for the TB-doped PPy, compared with PPy synthesized without TB. When used as supercapacitor electrodes, the TB-doped PPy hydrogel reaches maximal specific capacitance of 649 F/g at the current density 1 A/g. The result shows that PPy nanostructured hydrogels can be tuned for potential applications in next-generation energy-storage materials.

We synthesized a novel cage-ladder-structure, phosphorus-containing polyhedral oligomeric silsesquinoxane (CLEP-DOPO-POSS) via the hydrolytic condensation of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-vinyl trimethoxysilane (VTMS) with 2-(3,4-epoxycyclohexyl) ethyl trimethoxysilane and then incorporated it into epoxy resins (EPs) in different ratios with thermal curing technology. The structure of CLEP-DOPO-POSS was confirmed by Fourier transform infrared spectroscopy, NMR spectroscopy ( 1 H-NMR and 29 Si-NMR), matrix-assisted laser desorption ionization time-of-flight, and X-ray diffraction. The thermal stability, mechanical properties and flame retardancy effect of CLEP-DOPO-POSS on EP were comprehensively evaluated via thermogravimetric analysis (TGA), dynamic mechanical analysis, universal tensile testing, limiting oxygen index (LOI) measurement, UL-94 testing, and cone calorimetry. The flame-retardant mechanism of the EP modified with CLEP-DOPO-POSS was investigated by TGA-IR, TGA-mass spectrometry, and scanning electron microscopy. The experimental results show that CLEP-DOPO-POSS was homogeneously dispersed in the EP matrix. The LOI value reached 31.9, and the UL-94 grade passed V-0 with the presence of only 0.28% P (2.91 phr CLEP-DOPO-POSS). In addition, the EP composite containing CLEP-DOPO-POSS exhibited a better thermal stability and mechanical properties. The flameretardant mechanism was attributed to the quenching effect of the phosphorus-containing free radicals and the formation of phosphorusand silicon-containing char layers in the condensed phase.

ABSTRCT: A novel redox system, potassium diperiodatocuprate [Cu (III)-chitosan], was employed to initiate the graft copolymerization of methyl acrylate (MA) onto chitosan in alkali aqueous solution. The effects of reaction variables such as monomer concentration, initiator concentration, pH and temperature were investigated. By means of a series of copolymerization reactions, the grafting conditions were optimized. Cu (III)-chitosan system was found to be an efficient redox initiator for this graft copolymerization. The structures and the thermal stability of chitosan and chitosan-g-poly(methyl acrylate) (PMA) were characterized by infrared spectroscopy (IR) and thermogravimetric analysis (TGA). In this article, a mechanism is proposed to explain the formation of radicals and the initiation. Finally, the graft copolymer was used as the compatibilizer in blends of poly-(vinyl chloride) (PVC) and chitosan. The scanning electron microscope (SEM) photographs and differential scanning calorimetry (DSC) thermograms indicate that the graft copolymer improved the compatibility of the blend.

P(NIPAM-co-FPA) contains an aldehyde group and a phenolic ester moiety is synthesized. The aldehyde group can form reversible covalent bonds with hydrazide to endow the polymer gels with self-healing properties. The self-healable polymer gel can be degraded in Na2CO3 solution based on cleavage of phenolic ester bond.