The modification of a polyimide (PI) membrane by aromatic amine vapor was performed in this work to increase the crosslinking of the membrane and to study the effect on gas permeability and the corresponding selectivity. The single-gas permeability of the membranes at 35 8C was probed for H 2 , O 2 , N 2 , CO 2 , and CH 4 . From the relationship between the combinations of gases and ideal permselectivities, this study showed that amine-crosslinked PI membranes tended to increase gas permselectivities exponentially with the increasing difference in gas kinetic diameter. Moreover, this study illustrated that the permeability of the membranes was influenced by the formation rate of amine-crosslinked networks or chemical structures after the reaction. The membranes had the highest level of permselectivities among crosslinked PI membranes for O 2 /N 2 , and the H 2 /CH 4 permselectivity increased 26 times after vapor modification. Furthermore, the modification method that used aromatic amine vapor produced thin and strongly modified layers. These findings indicate that modification is an advantageous technique for improving gas-separation performance, even considering thinning.

The characterization and gas permeation properties of ultraviolet (UV)‐cured fluorine‐containing telechelic polyimide membranes and end‐capped with a crosslinker with acryloyl groups were investigated. Membrane formation property was improved by the addition of crosslinker by using UV irradiation. The densities of UV‐cured membranes were almost similar to each other, and high gel fraction was shown on the UV‐cured membranes. This result suggests that the crosslinker promotes crosslink reaction at the polymer chain ends and does not induce appreciable membrane densification. Furthermore, the gas permeability of the UV‐cured membranes was higher than that of the membrane without the crosslinker. The higher gas permeability is due to the new crosslink structure formed at the polymer chain ends, which was promoted by the crosslinker after UV irradiation, but did not induce appreciable membrane densification. The use of a BEI crosslinker in the telechelic polyimide membranes promoted the crosslink reaction and increased the H2 selectivity because H2 permeability was not sensibly affected by the crosslink reaction. POLYM. ENG. SCI., 54:1089–1099, 2014. © 2013 Society of Plastics Engineers

Efficient electrodeposition can be accomplished using solid electrolyte deposition (SED) with a cation exchange membrane as an electrolyte because the electric field imposed on the electrolyte membrane can control the mass transfer of metallic ions. Salient benefits of SED include the following: (1) Pattern plating can be conducted easily. The handling of an electrochemical cell is extremely simple because of its solid electrolyte usage. (2) Post-treatment of the electrode is unnecessary because the solid electrolyte contacting the electrode surface can be removed after electrodeposition. (3) High-rated plating can be expected because the driving force of the mass transfer of the reactants is expected to be migration. To verify those benefits, electrochemical measurements were conducted. Current-potential curves show the current density in the SED to be higher than that obtained using copper electrodeposition in the same concentration of CuSO 4 solution as that for the SED. Moreover, the patterning was easy. Post-treatment was unnecessary because copper was deposited only on the substrate contacted with the solid electrolyte. We propose a mass transfer mechanism that occurs during SED processing using a solid electrolyte. The relation between overvoltage and the current density during SED is explained clearly by the mechanism.

Copper plating is generally used for the fabrication of a printed circuit board of electronic device. The patterning is carried out by masking with insulator for the partial plating on the substrate. Solid electrolyte deposition (SED) method using solid electrolyte instead of liquid electrolyte is strong candidate for an alternative plating technique without masking because the copper is deposited only on the substrate contacted with solid electrolyte. Figure 1 shows the scheme of electrochemical cell for copper SED. The electrochemical cell is quite simple, namely, a thin solid electrolyte membrane is sandwiched by substrate and counter electrode. The substrate works as a cathode during copper deposition. Copper plate is used for the counter electrode because cupric ions are dissolved into the solid electrolyte membrane by the anodic reaction. Cation-exchange membrane is used for the solid electrolyte since the mass transfer of cupric ions is controlled by migration originating from the voltage between two electrodes. The solid electrolyte membrane is immersed in CuSO4solution to absorb cupric ion by ion-exchange for over 24 hours before the polarization. The copper is deposited on the substrate when the potentiostatic polarization is performed. Advantages of SED comparing with common electro-deposition are written as follows. ・Electrochemical cell is very simple. ・Post-processing is simple because of no masking. ・It’s environment-friendly because of a small quantity of liquid． ・The deposition rate is very fast because driving force of mass transfer of cupric ions is migration and the concentration of cupric ions is maintained constantly in the solid electrolyte membrane. The deposition rate is determined by three steps, which are anodic dissolution of copper counter electrode, the mass transfer of cupric ions in solid electrolyte membrane and the cathodic reaction on the substrate. Therefore, the measurements of 3D electrochemical impedance were carried out to discriminate above-mentioned three contributions to the deposition rate of copper by SED. Reference: 1) K. Akamatsu, Y. Fukumoto, T. Taniyama, T. Tsuruoka, H. Yanagimoto, H. Nawafune, Langumuir, 27, 11761-11766 (2011). Figure 1

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