Diffusion study of iodine and antimony pentafluoride in polyacetylene

Benoît, C.; Rolland, M.; Aldissi, M.; Rossi, Andrea Mario; Cadéne, M.; Bernier, P.

doi:10.1002/pssa.2210680128

Cited by 72 publications

(11 citation statements)

References 7 publications

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“…At low frequencies and for very thick samples, the diffusivity of the moving species in the system is expressed as follows (17) D = t2/3RLCL when ~o << 2D/t 2 [3] The diffusivities calculated using the t, RL, and CL values in Tables II and III are 1.14 • 10 .6 and 5.65 • 10 -7 cm2/s for tl = 0.011 cm and t2 = 0.0025 cm, respectively. These values are typical for diffusion of dopant species within the pores ofa PA film (10 _7 to 10 8 cm2/s) (18,19) but are much higher than values measured for solid-state diffusion of ions within PA fibrils (10 12 cm2/s) (20). Thus, even though the pores between fibrils do not appear to contribute to the double layer capacitance measured at high doping level and moderate to high frequency, the electrolyte-filled pores are evidently available to aid in the diffusion of cations at low frequency.…”

Section: Re(z) (Ohm)mentioning

confidence: 99%

Electrochemical Characteristics of Alkali‐Metal Doped Polyacetylene Electrodes

Jow¹,

Shacklette²

1988

J. Electrochem. Soc.

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The doping and undoping characteristics of alkali-metal doped polyacetylene are investigated using cyclic voltammetry and complex impedance measurement techniques. Reversibility, charge transfer resistance (Rct), double layer capacitance (Col), and general impedance behavior are discussed:Polyacetylene (PA) can be either partially oxidized or reduced electrochemically (1). When oxidized or reduced, PA becomes conductive with the appropriate counterion being inserted from the electrolyte. Its potential application to energy storage devices has spurred extensive studies on its electrochemical properties. Most studies have been concentrated on oxidized polyacetylene (2-5), which can be used as a cathode in secondary batteries. However, studies on reduced polyacetylene have also attracted attention (5-7). A variety of cations are suitable as counterions for the partially reduced polymer. These include alkali-metal ions and a number of organocations such as alkylammonium, immidazolium, peridinium, sulfonium, and the like. The doping (reduction) and undoping (oxidation) reaction can be represented as followswhere M § is most typically Li § Na § or K § y is the fractional charge per repeat unit, and x is the degree of polymerization. The reduced polymer has been suggested as an anode in secondary batteries (7). In the present work, the basic electrochemical doping and undoping characteristics of PA by alkali metals are studied using cyclic voltammetry and complex impedance measurements. ExperimentalPolyacetylene in the form of freestanding film was prepared using the standard Shirakawa technique (8). After preparation, the film was stored in a refrigerator at a temperature of -40~ inside a dry box before use. Polyacetylene electrodes were constructed from films having a thickness of 0.003 cm and an area of 0.5 • 0.5 cm 2 and were wrapped with expanded nickel metal. Thicknesses were measured with a micrometer exerting gentle pressure in order to minimize compression of the porous structure. Solvents used for the electrolyte solution were tetrahydrofuran (THF) or 2-methyltetrahydrofuran (2-MTHF). These solvents were distilled from a solution with sodium benzophenone. The salts, lithium tetrabuty]borate, LiB(C4Hg)4, and sodium tetraphenylborate, NaB(C~H~)4, purchased from Alfa, were used without further treatment. Potassium tributylpyrrolylborate, KB(C4Hg)3(C4H4N), was prepared in this laboratory according to the procedure by Klemann et al. (9). Each solution was stirred with its alkalimetal amalgam and filtered before use.A three-electrode cell having the configuration sketched in Fig. 1 was used in all of the electrochemical studies. The working electrode v~as a polyacetylene film with typical *Electrochemical Society Active Member. area 0.5 • 0.5 cm 2 wrapped with expanded nickel metal. Alkali metal held within a polyethylene tube was used as a reference electrode. Two alkali-metal foils were positioned on both sides of the working electrode as counterelectrodes. The cell was contained in a glass cell with a Kalrez O-ri...

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Section: Re(z) (Ohm)mentioning

confidence: 99%

Electrochemical Characteristics of Alkali‐Metal Doped Polyacetylene Electrodes

Jow¹,

Shacklette²

1988

J. Electrochem. Soc.

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“…l -3 In chemical doping typically a solid polymer film is contacted with a reactive liquid or vapor to create mobile charge carriers on the polymer chains. 12 antimony profiles in microfibrillar SbF5-doped polyacetylene films. With regard to diffusion several complexities are associated with the chemical doping process.…”

Section: Introductionmentioning

confidence: 99%

Dopant concentration profiles in conducting poly(p-phenylenevinylene) by Rutherford backscattering spectrometry

Masse¹,

Composto²,

Jones³

et al. 1990

Macromolecules

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Elemental depth profiles have been obtained from AsFS-doped poly@-phenylenevinylene) films by using Rutherford backscattering spectrometry. Shallow arsenic penetrations were achieved with the AsF6 source maintained at a temperature less than -53 O C . The arsenic penetration in a film doped for 10 days was approximately 1 pm. Further, the arsenic profiles are not characteristic of either Fickian or case I1 diffusion.A significant amount of oxygen is incorporated in these doped films. The RBS spectra indicated oxygen to be confined to the doped f i l m surface layer (= 60 nm). This is consistent with the formation of surface arsenic oxide species. Nearly constant arsenic and fluorine concentrations are observed just below the film surface for relatively heavy dopings. These results suggest one AsFs-anion for every four to five PPV repeat units. When the measured dopant penetration is used, the lower limit to the intrinsic electrical conductivity of AsFsdoped PPV is estimated to be 4 X 104 ( Q cm)-l.

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“…They found a diffusion coefficient D in the order, 1014-10 -c~ cm2/sec. Benoit et al [12] used Castaing microprobe analysis to measure the iodine concentration profile along thickness direction of cir-rich PA films for various doping time at room temperature and the vapor pressure of iodine at 0.309 torr. From the plot of mean dopant concentration versus square root of time, a diffusion coefficient of 10 7 cm2/sec was obtained.…”

Section: Introductionmentioning

confidence: 99%

“…Various degree of doping can impart various level of conductivity improvement [1]. Studies on the structure and characterization of the iodine-doped PA are extensive [2][3][4][5][6][7][8][9][10], but on the dynamics and mechanism of the vapor sorption are limited [11][12][13]. Kiess et al [11] measured weight uptake by monitoring the thickness increase of cis-rich PA film (which was deposited onto a quartz resonator) during iodine doping under the low vapor presssre, 0.05-0.2 torr at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of iodine vapor sorption in polyacetylene

Chen

Chan

1994

J Polym Res

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Simultaneous measurements of weight uptake and conductivity variation during iodine vapor sorption of polyacetylenes (PA) at 20-25°C show that the sorption is a two-stages process. For the first stage, iodine diffusion to the fibrilar surface of the cis-rich and trans-rich PA is of Knudsen type pore diffusion as supported by the sorption measurements of hexane for the cis-rich PA, and has a diffusion coefficient in the order of 107 cmZ/sec. Conductivity of the PA rises rapidly and reaches a maximum at end of the stage. For the second stage, the diffusion is more restrictive and has a diffusion coefficient lower than the first stage by a factor of about 10 due to multilayer sorption of iodine, which leads to a decrease in the pore diameter and therefor the diffusion rate. In addition to the restricted diffusion in the second stage, diffusion of the iodine molecules adsorped on the fibrilar surface into the interior of the fibrils is appreciable for cis-rich PA (leading to a conductivity drop) and is negliglible for tran-rich PA (leading to insignificant variation in conductivity).

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Diffusion study of iodine and antimony pentafluoride in polyacetylene

Cited by 72 publications

References 7 publications

Electrochemical Characteristics of Alkali‐Metal Doped Polyacetylene Electrodes

Electrochemical Characteristics of Alkali‐Metal Doped Polyacetylene Electrodes

Dopant concentration profiles in conducting poly(p-phenylenevinylene) by Rutherford backscattering spectrometry

Mechanism of iodine vapor sorption in polyacetylene

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