We report the preparation of a novel cross-linked anion exchange membrane (AEM) from poly(acrylonitrile)-co-poly(2-dimethylamino)ethyl methacrylate (PAN-co-PDMA) copolymer by quaternizing the DMA moieties followed by cross-linking of -CN groups. This process avoids the use of the carcinogenic reagent, chloromethyl ether (CME) which is widely employed for the chloromethylation reaction in the preparation of AEMs. Key parameters were evaluated via electrodialysis (ED) during water purification and revealed that a copolymer containing 28 wt% PDMA possesses all the required properties of a high performance AEM, such as, reasonable water uptake (21%), good ion-exchange capacity (IEC ¼ 1.30 m eq g À1 ), high ionic conductivity (K m ¼ 2.22 mS cm À1 ), a high transport number (t À ¼ 0.88) and good mechanical properties (9.2 MPa of tensile stress at break and 2.4 Kg cm À2 of burst strength in the water wet state). The AEM was directly tested in an ED unit in the recirculation mode by varying the concentration of the NaCl feed and the applied potential, showing a current efficiency as high as 80%. Such combination of physical and electrochemical properties of the membrane is attributed to its co-continuous morphology and its low degree of phase separation as confirmed by swelling, differential scanning calorimetry, the homogeneous distribution of oppositely charged dye and by the transparency of the membrane in both the dry and swelled states.

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Three types of silver/polymer nanocomposite films were prepared: (1) silver/polymethyl methacrylate, (2) silver/polystyrene, and (3) silver/polyt‐butyl methacrylate by mixing colloidal solution of functionalized Ag nanoparticles with solution of pre‐made polymers. The nanoparticles are randomly dispersed into the matrices. The desired surface functionality of Ag nanoparticle was achieved by using specific amphiphilic block copolymer (specific hydrophobic block part) as stabilizer. The stability of nanoparticles in these host hydrophobic polymer matrices was determined after annealing the nanocomposite films at high temperature. The nanoparticles remained stable and no agglomeration occurred upon annealing up to 120°C. Up to 20 wt% of block copolymer stabilized Ag nanoparticles (11% Ag) was successfully loaded in the polymer matrix. Such a dispersion of Ag nanoparticles into a hydrophobic polymer matrix significantly enhances the mechanical properties of the nanocomposite films. The storage and loss modulus increase with increasing Ag nanoparticles content. Compared with a polymer matrix, the polymer/Ag nanocomposites film (containing 0.65% of Ag) prepared by this method displayed storage modulus that are up to 130% higher. This is attributed to the high surface area of the polymer coated Ag nanoparticles in the polymer matrix and van der Waal's attraction force between surface of Ag nanoparticles (polymer brush) and host polymer matrix. Comparison of thermal properties of polymer and polymer/Ag nanocomposite films showed that the thermal stability of nanocomposites increases by about 20°C. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

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