Studies on syntheses and permeabilities of special polymer membranes. V. Effect of casting solution composition on permeation characteristics of cellulose acetate membranes in separation of aqueous polymer solutions

The permeation characteristics of cellulose acetate membranes in separation of polymers from their aqueous solutions were investigated by changing the preparation conditions of the membranes, that are the solvent evaporation period and the casting solution composition consisting of a mixture of cellulose acetate (CA), acetone (A), and formamide (FA). The rates of pure water permeability were influenced remarkably by the solvent evaporation period and the casting solution composition. When the solvent evaporation period was short, the rates of pure water permeability increased with a decrease in A/CA, increase in FA/A, and increase in FA/CA in the casting solution. From the experimental results using poly(vinyl alcohol) as poly(ethylene glycol) as feed solute, it was seen that the changes of solvent evaporation period and casting solution composition related to the change of microporous structure of the resulting membranes. The effect of feed concentration and operating pressure on the permeation characteristics were also studied. There was found a concentration polarization of poly(vinyl alcohol) molecules on the surface of the membrane, and a compaction of the membrane occurred under pressure.     

Studies on syntheses and permeabilities of special polymer membranes: 38. Formation mechanism of finger-like cavities in membranes from cellulose nitrate and single solvent

The relationship between the permeation characteristics of an aqueous polymer solution and the asymmetric structure of cellulose nitrate membranes was investigated under various conditions. The conditions and mechanism of the formation of finger-like cavities in cellulose nitrate membranes are discussed in some detail.     

Preparation and Characterization of Hybrid Quaternized Chitosan/Acrylic Resin Emulsions and their Films

An acrylic resin emulsion containing a quaternary ammonium salt (hybrid q‐chitosan/acrylic resin emulsion) was prepared by emulsion polymerization using an acrylic monomer with and without DAAM. DAAM was used to incorporate a functional keto group into the acrylic resin emulsion. Furthermore, a hybrid chitosan/acrylic resin emulsion was prepared for comparison. The elution of q‐chitosan in water from the acrylic resin film with a keto group was less than that from the acrylic resin emulsion without a keto group. In addition, the mechanical properties of the hybrid q‐chitosan/acrylic resin film could be modified by q‐chitosan that was crosslinked between acrylic resin particles. Furthermore, hybrid q‐chitosan/acrylic resin films had adsorption ability for formaldehyde, and the antimicrobial properties of these films were superior to those of the hybrid chitosan/acrylic resin film.

     

Al2O3-coated nanoporous TiO2 electrode for solid-state dye-sensitized solar cell

This paper reports the preparation of a core-shell nanoporous electrode consisting of an inner TiO₂ porous matrix and a thin overlayer of Al₂O₃, and its application for solid-state dye-sensitized solar cell using p-CuI as hole conductor. Al₂O₃ overlayer was coated onto TiO₂ porous film by the surface sol–gel process. The role of Al₂O₃ layer thickness on the cell performance was investigated. The solar cells fabricated from Al₂O₃-coated electrodes showed superior performance to the bare TiO₂ electrode. Under illumination of AM 1.5 simulated sunlight (89 mW/cm²), a ca. 0.19 nm Al₂O₃ overlayer increased the photo-to-electric conversion efficiency from 1.94% to 2.59%.