Solid-state and flexible zinc carbon (or Leclanche) batteries are fabricated using a combination of functional nanostructured materials for optimum performance. Flexible carbon nanofiber mats obtained by electrospinning are used as a current collector and cathode support for the batteries. The cathode layer consists of manganese oxide particles combined with single-walled carbon nanotubes for improved conductivity. A polyethylene oxide layer containing titanium oxide nanoparticles forms the electrolyte layer, and a thin zinc foil is used as the anode. The battery is shown to retain its performance under mechanically stressed conditions. The results show that the above configuration can achieve solid-state mechanical flexibility and increased shelf life with little sacrifice in performance.

Poly(vinylidene fluoride) (PVDF) nanofibers were prepared by electrospray deposition (ESD). To control the diameter, morphology, and structure of PVDF nanofibers, some parameters were investigated, such as polymer concentration, nozzle‐to‐ground collector distance, feeding rate of the polymer solution, and applied voltage. The fabricated fiber was 80–700 nm in diameter. The increase in the polymer concentration caused an increase in the polymer viscosity and fiber diameter. At low polymer concentration (5 wt %), polymer nanoparticles were formed. An increase in applied voltage will increase the fiber diameter. Variation in the nozzle‐to‐ground collector distance did not result in significant changes in the fiber diameter. Increase in the feeding rate of the polymer solution decreased the fiber diameter. Differential scanning calorimetry (DSC) and wide angle X‐ray diffraction (WAXD) measurements showed that the melting point and total crystallinity were decreased. Fourier transform infrared spectroscopy (FTIR) measurement revealed that ESD process induced the formation of the oriented β‐phase PVDF structures. It was also demonstrated that the addition of hydrofluorocarbon solvent to polymer solution remarkably enhanced the formation of β‐phase crystalline structure of PVDF nanofiber. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 779–786, 2006

Anionic and cationic monomers were graft-polymerized onto poly(acrylonitrile) (PAN) membrane surfaces. The graft polymerization was initiated by an oxidation−reduction system at 25 °C. Grafted PAN membrane surfaces yielded FT-IR/ATR spectra clearly different from that of an unmodified PAN membrane, because of the presence of the graft chains. ζ potentials of the pore surfaces of the grafted PAN membranes were obtained from streaming potential measurements. The surface properties are discussed with respect to a single site dissociation model, which is based on the protonation and deprotonation of charged surface groups. In this study, we obtained some characteristic parameters of the pore surfaces from the theoretical fits using the site dissociation model. This approach gives direct insight into the pore surface properties of the membrane. The results could be well explained by an ion-pairing effect in terms of different charge characteristics between membranes having hydrophobic or hydrophilic graft chains:  charge groups of hydrophobic graft chains are likely to form ion pairs with counterions from the external solution. The local dielectric constant surrounding ion pairs plays an important role in the surface effective charge concentration.

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Electrospinning is a versatile method for forming continuous thin fibers based on an electrohydrodynamic process. This method has the following advantages: (i) the ability to produce thin fibers with diameters in the micrometer and nanometer ranges; (ii) one-step forming of the two- or three-dimensional nanofiber network assemblies (nanofibrous membranes); and (iii) applicability for a broad spectrum of molecules, such as synthetic and biological polymers and polymerless sol-gel systems. Electrospun nanofibrous membranes have received significant attention in terms of their practical applications. The major advantages of nanofibers or nanofibrous membranes are the functionalities based on their nanoscaled-size, highly specific surface area, and highly molecular orientation. These functionalities of the nanofibrous membranes can be controlled by their fiber diameter, surface chemistry and topology, and internal structure of the nanofibers. This report focuses on our studies and describes fundamental aspects and applications of electrospun nanofibrous membranes.

The graphene nanoribbon (GNR)/carbon composite nanofiber yarns were prepared by electrospinning from poly(acrylonitrile) (PAN) containing graphene oxide nanoribbons (GONRs), and successive twisting and carbonization. The electrospinning process can exert directional shear force coupling with the external electric field to the flow of the spinning solution. During electrospinning, the well-dispersed GONRs were highly oriented along the fiber axis in an electrified thin liquid jet. The addition of GONRs at a low weight fraction significantly improved the mechanical properties of the composite nanofiber yarns. In addition, the carbonization of the matrix polymer enhanced not only the mechanical but also the electrical properties of the composites. The electrical conductivity of the carbonized composite yarns containing 0.5 wt % GONR showed the maximum value of 165 S cm(-1). It is larger than the maximum value of the reported electrospun carbon composite yarns. Interestingly, it is higher than the conductivities of both the PAN-based pristine CNF yarns (77 S cm(-1)) and the monolayer GNRs (54 S cm(-1)). These results and Raman spectroscopy supported the hypothesis that the oriented GONRs contained in the PAN nanofibers effectively functioned as not only the 1-D nanofiller but also the nanoplatelet promoter of stabilization and template agent for the carbonization.

The conductance and counterion activity of aliphatic ionenes with counterions of F-, Cl-, Br-, I-, and NO3 - in both the absence and presence of salts were measured and compared with Manning's equations for both cases. Samples used were 3,3-, 4,5-, 6,6-, and 6,9-ionenes, where the numbers are those of methylene groups between the quaternized nitrogen atoms. The activity coefficients of counterions for ionenes in the absence of salts were lower than the theoretical values, and experimentally determined values of the charge density parameters, higher than the theoretical ones, could explain the departure between the experimental and the theoretical values at least semiquantitatively. The conductance of ionenes in the presence of salts deviated from the additivity rules, dependent on charge density of the ionenes as well as the counterions used. It also deviated from the theoretical prediction in which the interaction between small ions was taken into account. On the other hand, the additivity holds approximately for the counterion activity irrespective of the species of ionenes and counterions, in marked contrast to the case of conductivity. The viscosity of the ionene solution exhibited a strong dependence on the salts added. The effect of salts on the viscosity was more prominent in the samples with higher charge density parameter, corresponding to larger conformational change in the polyion. These results may give useful information on the conformation of ionenes in solution as well as the mechanism of the electrical conductivity of polyelectrolytes.

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