Surface modification of halogenated polymers: 1. Polytetrafluoroethylene

Brace, Karen; Combellas, Catherine; Dujardin, Erik; Thiébault, A.; Delamar, Michel; Kanoufi, Frédéric; Shanahan, M. E. R.

doi:10.1016/s0032-3861(96)00889-0

Cited by 27 publications

(19 citation statements)

References 12 publications

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“…Even though a simplified nucleation model was adopted, the SECM setup seems a promising tool for the quantitative investigation of phase transformation kinetics. 2(2 + δ)πC P d (27) …”

Section: Discussionmentioning

confidence: 99%

“…[5][6][7][8][9][10][11][12][13][14][15][16] Reductive heterogeneous treatments have been carried out: (i) at the interface between the polymer and an amalgam of alkali metals [16][17][18][19] or (ii) at a metallic electrode located at the contact of the polymer. [20][21][22][23][24] Reductive homogeneous treatments are generally achieved by alkali metals dissolved in liquid ammonia [25][26][27] or radical-anions in the presence of alkali cations in an organic solvent. 10,28 The reductive reagent can be generated either chemically in the whole solution, electrochemically in the vicinity of the polymer via a cathode, 29 using a band ultramicroelectrode mounted on the same plane as the polymeric surface, 30 or via scanning electrochemical microscopy.…”

Section: Introductionmentioning

confidence: 99%

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Surface Modification of Halogenated Polymers. 8. Local Reduction of Poly(tetrafluoroethylene) by the Scanning Electrochemical Microscope − Transient Investigation

Combellas¹,

Kanoufi²,

Mazouzi³

2004

J. Phys. Chem. B

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Local reduction of poly(tetrafluoroethylene) (PTFE) was achieved by scanning electrochemical microscopy (SECM). The PTFE reduction process was analyzed by the current transients, which helped propose general trends for PTFE microfabrication. The SECM was used to investigate quantitatively the kinetics of PTFE phase transformation. In a short time, a nucleation process accounts for the PTFE reduction evolution. The nucleation rate follows a potential dependency similar to that observed for conducting polymer growth or metal deposition. At long time, the expansion of the PTFE carbonization proceeds in a hemi-ellipsoidal fashion, the radial expansion being much easier than the in-depth one. Those expansions can be correlated to the tip current when changing reduction time, reducing species concentration, nature of the electrolytic solution, SECM tip radius, and tip-substrate separation. The stoichiometry of the reduction was estimated, and the existence of two kinetic regimes owing to the redox mediator reduction potential was evidenced, which confirmed previous results by feedback experiments. A rough model was proposed in which the reduction along the in-depth direction is mainly controlled by a diffusive process while the material resistivity controls the radial expansion. The observed variations may be explained by penetration of the reducing species into the rough reduced PTFE material.

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“…Even though a simplified nucleation model was adopted, the SECM setup seems a promising tool for the quantitative investigation of phase transformation kinetics. 2(2 + δ)πC P d (27) …”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Surface Modification of Halogenated Polymers. 8. Local Reduction of Poly(tetrafluoroethylene) by the Scanning Electrochemical Microscope − Transient Investigation

Combellas¹,

Kanoufi²,

Mazouzi³

2004

J. Phys. Chem. B

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“…These techniques include treatments with plasmas [23], X-ray [24], ion beam [25], and UV irradiation [26]; electrochemical reduction [27]; wet chemical etching with solvated electrons in liquid ammonia [28], sodium naphthalene [29], and benzoin dianion [30]. All these methods damage the surface in non-selective ways.…”

Section: Functionalization Without Lightmentioning

confidence: 99%

Functionalization of saturated fluorocarbons with and without light

Chen

Lemal

2006

Journal of Fluorine Chemistry

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“…This may be performed by solvated electrons (see also refs. [2,3]) or by generating radical anions in liquids or in solid electrolytes. PTFE surfaces may also be directly reduced in DMF/NBu 4 BF 4 into a carbonized material by an electrode poised at a potential more negative than À 2.5 V versus SCE and placed in straight contact with the PTFE.…”

Section: Polytetrafluoroethylene (Ptfe or Teflonmentioning

confidence: 99%

Micrometrically Controlled Surface Modification of Teflon ^® by Redox Catalysis: Electrochemical Coupling between Teflon ^® and a Gold Band Ultramicroelectrode

Amatore

Combellas

Kanoufi

et al. 2000

Chemistry A European J

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Carbon-fluorine bonds of Teflon (polytetrafluoroethylene, PTFE) can be reduced electrochemically with the purpose of modifying its adhesive and wetting surface properties by micrometrically controlled surface carbonization of the material. This can be performed adequately by redox catalysis provided that the redox mediator couple has a sufficiently negative reduction potential. The process is investigated kinetically with benzonitrile as the mediator and a gold-band ultramicroelectrode mounted adjacent to a PTFE block, though separated from it by an insulating micrometric mylar gap. For moderate fluxes of reduced mediator, the whole device behaves as a generator-collector double-band assembly with a constant current amplification factor. This is maintained over long periods of time, during which the carbonized PTFE zones extends over distances that are much wider than the slowly expanding cylindrical diffusion layer generated at the gold-microband electrode. This establishes that the overall redox catalysis proceeds through electronic conduction in the n-doped carbonized material. Thus, carbonization progresses at the external edge of the freshly carbonized surface in a diffusion-like fashion (dependence on the square root of time), while the redox-mediator oxidized form is regenerated at the carbonized PTFE edge facing to the gold ultramicroelectrode, so that the overall rate of carbonization is controlled by solution diffusion only. For larger fluxes of mediator, the heterogeneous rate of reduction and doping of PTFE becomes limiting, and the situation is more complex. A conceptually simple model is developed which predicts and explains all the main dynamic features of the system under these circumstances and allows the determination of the heterogeneous rate constant of carbon-fluorine bonds at the interface between the carbonized zone and the fresh PTFE. This model can be further refined to account for the effect of ohmic drop inside the carbonized zone on the heterogeneous reduction rate constants and henceforth gives an extremely satisfactory quantitative agreement with the experimental data.

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Surface modification of halogenated polymers: 1. Polytetrafluoroethylene

Cited by 27 publications

References 12 publications

Surface Modification of Halogenated Polymers. 8. Local Reduction of Poly(tetrafluoroethylene) by the Scanning Electrochemical Microscope − Transient Investigation

Surface Modification of Halogenated Polymers. 8. Local Reduction of Poly(tetrafluoroethylene) by the Scanning Electrochemical Microscope − Transient Investigation

Functionalization of saturated fluorocarbons with and without light

Micrometrically Controlled Surface Modification of Teflon ^® by Redox Catalysis: Electrochemical Coupling between Teflon ^® and a Gold Band Ultramicroelectrode

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Surface modification of halogenated polymers: 1. Polytetrafluoroethylene

Cited by 27 publications

References 12 publications

Surface Modification of Halogenated Polymers. 8. Local Reduction of Poly(tetrafluoroethylene) by the Scanning Electrochemical Microscope − Transient Investigation

Surface Modification of Halogenated Polymers. 8. Local Reduction of Poly(tetrafluoroethylene) by the Scanning Electrochemical Microscope − Transient Investigation

Functionalization of saturated fluorocarbons with and without light

Micrometrically Controlled Surface Modification of Teflon ® by Redox Catalysis: Electrochemical Coupling between Teflon ® and a Gold Band Ultramicroelectrode

Contact Info

Product

Resources

About

Micrometrically Controlled Surface Modification of Teflon ^® by Redox Catalysis: Electrochemical Coupling between Teflon ^® and a Gold Band Ultramicroelectrode