Combined polyethylene-polyaniline membranes

Abstract

We previously developed a technique for the prepara-and electrolytes) were produced in the following way. A thin PANI layer was deposited on the PE membrane tion of microfiltration membranes of low-density polyethylene (PE) involving melt extrusion at a high flow surface from an aqueous dispersion of PANI with particles of about 0.3 micron in size, obtained by polymeriz-velocity with subsequent annealing, drawing, and thermal stabilization. 1,2 The microporous films obtained by ing aniline in an aqueous solution of poly(vinyl alcohol) (PVA). 8 The layer of thickness of 4-7 microns, con-this technique have a mean pore size of 0.045 microns, high permeability, small thickness, and good mechani-sisting of PANI particles embedded in the PVA matrix, revealed high adhesion to the PE membrane surface. cal properties. Owing to these parameters, the films can be efficiently used as a support for depositing aThe adhesion remained high also upon exposure to solvents such as ethyl alcohol and propylene carbonate, layer of another polymer which is either unable to form film or the film made from it has poor mechanical char-and no peeling of the PANI-containing layer occurred even upon breakdown of the membrane. acteristics but reveals separating (''membranelike'') properties. Such a polymer is polyaniline (PANI), It should be noted that conventional PE films obtained by melt extrusion exhibit low adhesion to the which is able not only to retain or to exchange anions under an applied voltage 3 or without it, 4 but also to majority of polymeric and nonpolymeric materials. Actually, a PANI-containing layer formed by the same separate neutral species (solutes and gases). 5-7 The first case is associated with the change of pK a , and the way as onto PE membranes is readily separated from both as-spun and annealed PE films. On the other hand, second case is connected with the variation of polymer morphology upon changes in the degree of oxidation of a film of neat PVA exhibits poor adhesion not only to the conventional PE films, but also to the surface of PE PANI. The utilization of the useful separating properties of PANI, however, is hindered by the poor process-membranes. These facts allow one to suggest that the reasons of the high adhesion of the PANI-containing ability and poor mechanical properties. Thus, the preparation of combined PE-PANI membranes represents layer are associated to both the highly developed surface of the PE membrane and the peculiarities of the considerable scientific and practical interest. It should be noted that, to the best of our knowledge, no informa-structure of PANI-containing layer. The electrical conductivity of the PANI-containing tion on the preparation of PE-PANI membranes is available at present. layer of combined membranes measured by a conven-In this article, we now report a method for the prepational four-probe technique ( s Å 0.2 S/cm) is equal to ration of combined membranes on the basis of a mithat of a film cast from the initial PANI dispersion. crofiltration PE membrane and PANI. Co...

Composite Membranes Prepared from Cation Exchange Membranes and Polyaniline and Their Transport Properties in Electrodialysis

“…Pyrrole and aniline are easily polymerized by electrochemical 7 or chemical oxidation, 8 and the resulting polyaniline and polypyrrole are typical functional polymers. Thus, the polymers have also been applied to various separation membranes: membranes with different dopants for gas separation, 9 a microfiltration membrane combining microporous polyethylene with polyaniline, 10 anion exchange membranes composed of anion exchange membranes and polypyrrole for acid concentration by electrodialysis, 11 ion gate membranes, 12 membranes for pervaporation, 13 etc. It is possible to give new functions to the separation membranes by combining the conducting polymers and the cation exchange membrane.…”

Advances in Polyaniline for Biomedical Applications

“…Dispersion polymerization: the first paper describing the preparation of PANI dispersion is dates back 1983 by Armes and Aldissi [93]. Since then numerous works have been published and this method has been deeply investigated because the final materials find application in strategical fields, such as membranes [94,95], anticorrosion protection metals [96,97], printable sensors [95,98], etc. The reaction consists in the oxidative polymerization of aniline monomer by stoichiometric oxidants (generally ammonium persulfate) in an acidic aqueous medium containing a proper steric stabilizer (typically a water soluble polymer).…”

Molecular polymer–polymer compositions. Synthetic aspects

“…In particular, microporous PE films synthesised by rapid melt extrusion followed by annealing exhibit a well-developed surface and can be used as supports for composite materials prepared by coating these films with a thin layer (4 ± 7 mm) of conducting polyaniline (PAn) from aqueous dispersion. 288 This kind of material is characterised by strong adhesion between their components. Despite its very small thickness, the PAn layer has the same conductivity (0.2 O 71 cm 71 ) as that of a much thicker film cast from the PAn dispersion.…”