Mechanical Properties of Flexible Polypyrrole-Based Conducting Polymer Alloy Films

Abstract

ABSTRACT:The electrochemical polymerization of pyrrole on an electrode covered with an insulating polymer film ·produces conducting polymer alloy films of polypyrrole (PPy) and insulating polymer. By using vinylidene fiuoride-trifiuoroethylene copolymer (P(VDF-TrFE)) as an insulating polymer, very flexible and stretchable conducting films were obtained. The mechanical properties of the alloy films were studied by measuring tensile strength and dynamic modulus of elasticity. The excellent mechanical properties of P(VDF-TrFE) did not change by the incorporation of PPy up to a charge density of 0.5 C em-2 . A further increase of charge density caused a reduction of dynamic moduli of the alloy films. The alloy films with the charge density of 0.5 C em -2 extended more than 100% and their surface resistance was almost constant up to 50% elongation. The elongation more than 60% resulted in a large increase of surface resistance, because inhomogeneous fracture occurs from the electrode side of the film. A comparison of the mechanical properties between P(VDF-TrFE)-PPy and other alloy films based on poly( vinyl chloride) were also studied.KEY Many efforts have concentrated on the improvement of the film quality of PPy. Iwata et al. 4 obtained the flexible pure PPy with high conductivity more than 300 S em -1 by polymerizing pyrrole at a low temperature about -30°C.The most attractive feature of this electrochemical polymerization is the capability of forming various hybrid conducting materials with different types of polymers. By using polymeric anions as electrolyte, PPy-polymer anion complexes can be easily prepared, and flexible polymeric anions can improve the mechanical properties of PPy. Bates et a!. 5 reported that PPy-sulphonated styrene-(hydrogenated) butadiene tri-block copolymer complex becomes flexible and can be extended up to 400%. However, the electrical conductivity of PPy-polyanion becomes less than lO-2 S em -1 , which is lower by 4 orders of magnitude compared with PPy single film.Another type of hybrid material can be prepared by the electrochemical polymer-1293

An electrochemically synthesized conducting semi-IPN from polypyrrole and poly(vinyl alcohol)

“…For the s-IPN, the solution side (C) reveals cauliflower-like morphology almost similar to that observed for the pure polymer and again the electrode side shows no such pattern. In the s-IPN, the PPy-SS is electrochemically grown within the PVA-C network; according to the previous investigators, 46,47 the first layer of the polymer is deposited on the electrode lifting the insulating coating slightly, followed by the growth of the PPy within the insulating matrix. Therefore, the electrode side of the IPN resembles that of the pure polymer and shows no particular pattern by analogy.…”

Reply

“…PPy composite can also be prepared by using electrochemical or chemical methods. The electrochemical method usually results in conductive composites with good mechanical property and high conductivity,6–8 but ultra‐thin films of the host polymers are necessary and only composites as large as electrode area can be produced, which greatly impedes its mass production. The chemical oxidative method can be carried out through different ways 9, 10.…”

A conducting composite of polypyrrole with ultrahigh molecular weight polyethylene foam

“…On the other hand, conducting polymers have at least one of the following undesirable characteristics: (1) poor mechanical properties; (2) poor processability; or (3) very low environmental stability. In the last decade, a considerable number of studies on conducting polymers have been carried out to overcome these shortcomings by incorporating conducting polymer with other conventional polymers by various methods 10–27…”

“…The difficulties in the improvement of mechanical properties of PPy was usually overcome by preparing composites of PPy with a polymer having better mechanical properties through electrochemical and oxidative polymerization. In the electrochemical method, PPy can be electrochemically impregnated into the host polymer, which coats the electrode 7–19. There are, however, limitations regarding the practical applications of such composites in this method.…”

“…Polymer composites produced by chemical methods are found to be more attractive. Among these conductive composites, the host polymers used are PVC,10–17 porous crosslinked PS,2 PV alcohol,15 fluorine‐vinylidiene polymers and its copolymers,16 polyimide,18 poly(phenylene terephthalamide),19 PMMA and its copolymers,20 UHMWPE fibers and gels,21–23 cellulosic materials,24, 25 and Polycarbonate 26. The samples produced by the chemical oxidation polymerization of pyrrole with powder PE, PP, and also PMMA showed better conductivity than the blends prepared by mechanical mixing 27…”