Elongated Microcapsules and Their Formation

Elongated microcapsules, such as elongated hydrophobic-core and hydrophilic-core microcapsules, may be formed by pulse stirring an emulsion or shearing an emulsion between two surfaces moving at different velocities. The elongated microcapsules may be dispersed in a coating formulation, such as paint

Swelling behavior of PEMFC during conditioning

Polymeric cation exchange membranes (PEMFC) are used in fuel cell technology. These membranes act as a physical barrier between anode and cathode, but diffusion through the membrane should allow protons to be carried from anode to cathode at a rate sufficient to supply energy requirements. They avoid any direct reaction of oxygen and hydrogen that would diminish fuel cell efficiency. Membranes have to be conditioned before use. This conditioning step changes membrane counterions and modifies their water content, which has an effect on their diffusion coefficients. In order to analyse and quantify the effect of conditioning techniques on membrane performance various experiments with Nafion 117 cation exchange membranes were carried out. Membranes were conditioned using various methods to change the charged cation in the membrane. The reactives used were ultrapure water, nitric acid, hydrochloric acid, hydrogen peroxide, sodium chloride, potassium chloride and ethylene glycol, all at room temperature. Some conditioning methods were carried out using solvents heated to 100 ºC. Water content was indirectly monitored by measuring membrane swelling. Results show that membrane conditioning with strong acids followed by treatment with water increases membrane water content by about 5%. Using high-temperature treatment the water content also increases. Water uptake or release from membranes is analysed in terms of water activity

Highly Oriented Sulfonic Acid Groups in a Nafion Thin Film on Si Substrate

Solid state ionics is a research field attracting much current attentions because of the ideal power sources for use with portable electronic devices having high power-to-weight ratios. One of the most urgent subjects in this field is to understand proton transport properties at the interface between inorganic materials and polymer electrolyte from the viewpoint of developing much more powerful energy. In this study, a 150-nm-thick Nafion thin film was prepared by spincoating on a silicon (Si) substrate to investigate the proton transport property at the interface. The infrared (IR) p-polarized multiple-angle incidence resolution spectrometry (p-MAIRS) technique was applied to investigate the in-plane (IP) and out-of-plane (OP) spectra to the surface. The IP spectrum showed a well-known spectrum, but the OP spectrum was quite different from the IP spectrum. An anomalous IR peak was observed in the OP spectrum at 1260 cm^. From density functional theory (DFT) calculations, this peak was attributed to the −SO_3H vibration modes between two sulfonic acid groups with hydrogen bonds. These results demonstrate that the Nafion thin film on Si substrate had a highly oriented structure with the sulfonic acid groups at the side chain. Impedance measurements of Nafion thin film were conducted to investigate the proton transport property of the Nafion thin film on SiO_2 substrate. The proton conductivity of the thin film exhibited a lower value than that of the commercial Nafion membrane. The low proton conductivity of the Nafion thin film was related with these highly oriented structures