Chain Reorientation in Poly(tetrafluoroethylene) by Mobile Twin-Helix Reversal Defects

Kimmig, Martin; Strobl, G.; Stuehn, B.

doi:10.1021/ma00087a017

Cited by 71 publications

(116 citation statements)

References 14 publications

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“…This means that the concentration of the helix-reversal defects decreases after Zn infi ltration. A similar evolution in the Raman spectra of the native PTFE has been observed in the temperature range, -10 ° C < T < 60 ° C [ 41 ] or 9 ° C < T < 184 ° C, [ 28 ] which accompanies a phase transformation from a 15 7 hexagonal (phase IV) to a 13 6 triclinic (phase II) phase. The Raman spectra of the Zn-PTFE hybrid are notably similar to the spectra measured at -10 ° C [ 41 ] or 9 ° C, [ 28 ] although our Raman measurements were performed at room temperature.…”

Section: Resultssupporting

confidence: 73%

“…A similar evolution in the Raman spectra of the native PTFE has been observed in the temperature range, -10 ° C < T < 60 ° C [ 41 ] or 9 ° C < T < 184 ° C, [ 28 ] which accompanies a phase transformation from a 15 7 hexagonal (phase IV) to a 13 6 triclinic (phase II) phase. The Raman spectra of the Zn-PTFE hybrid are notably similar to the spectra measured at -10 ° C [ 41 ] or 9 ° C, [ 28 ] although our Raman measurements were performed at room temperature. In other words, after Zn incorporation, the native PTFE has transformed from the transitional phase II-IV into phase II (see Figure 1 ), which remains stable even at room temperature, although this phase is expected for native PTFE at much lower temperatures.…”

Section: Resultssupporting

confidence: 73%

“…[ 41 ] Notably, both bands exhibit an evolution of behavior after Zn infi ltration. Namely, the intensity of the defect-induced band (598 cm − 1 ) decreases after Zn infi ltration, whereas the band at 578 cm − 1 becomes sharper and stronger.…”

Section: Resultsmentioning

confidence: 99%

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An Alternative Route Towards Metal–Polymer Hybrid Materials Prepared by Vapor‐Phase Processing

Lee

Ischenko

Pippel

et al. 2011

Adv Funct Materials

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Transition metals incorporated into polymers lead to unusual or improved physical properties that significantly differ from those of purely organic polymers. A simple and practicable incorporation of diverse transition metals into any available polymer would make an important contribution to overcome some of the synthetic difficulties of metal‐polymer hybrid materials. Here, it is demonstrated that atomic layer deposition (ALD) can be a promising means to resolve some of those difficulties. It is found that even polytetrafluoroethylene (PTFE) with its great physical and chemical stability can be easily transformed into a transition metal–PTFE hybrid material simply by applying a metal‐oxide ALD process to PTFE. Upon metal incorporation into the PTFE, the molecular structure as well as mechanical properties (tensile behavior) of PTFE were observed to significantly change. For a better understanding of the changes to the material, experimental investigations using Raman spectroscopy, attenuated‐total‐reflection Fourier‐transform infrared spectroscopy, wide‐angle X‐ray diffraction, and energy‐dispersive X‐ray analysis were performed. In addition, with density functional theory calculations, potential bonding states of the incorporated metal into PTFE were modeled and predicted. The ALD‐based vapor‐phase approach for metal incorporation into a polymer could bring about rapid progress in the research area of metal–polymer hybrid materials.

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Section: Resultssupporting

confidence: 73%

Section: Resultssupporting

confidence: 73%

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An Alternative Route Towards Metal–Polymer Hybrid Materials Prepared by Vapor‐Phase Processing

Lee

Ischenko

Pippel

et al. 2011

Adv Funct Materials

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“…Peak assignments were made based on published X-ray data on undeformed PTFE powder, filaments and thin films [29][30][31][32][33].…”

Section: Discussionmentioning

confidence: 99%

In-situ Measurement of Crystalline Lattice Strains in Polytetrafluoroethylene

et al. 2007

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Strain measurements by neutron diffraction are employed as an in situ technique to obtain insight into the deformation modes of crystalline domains in a deformed semi-crystalline polymer. The SMARTS (Spectrometer for MAterials Research at Temperature and Stress) diffractometer has been used to measure the crystalline lattice displacements in polytetrafluoroethylene (PTFE) for crystalline phase IV (at room temperature) in tension and compression and for crystalline phase I (at 60°C) in compression. The chemical structure of PTFE, -(C 2 F 4 )-n , makes it ideally suited for investigation by neutron methods as it is free of hydrogen that results in limited penetration depths and poor diffraction acquisition in most polymers. Deformation parallel to the prismatic plane normals is shown to occur by inter-polymer chain compression with a modulus ∼10× bulk, while deformation parallel to the basal plane normal occurs by intra-polymer chain compression with a modulus ∼1000× bulk, corresponding with theoretical values for a PTFE chain modulus. Deformation parallel to the pyramidal plane normals is accommodated by interpolymer chain shear.

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“…(Figures 3a and 3b) whereas either the helix loss (Figures 4c and 4d) or the charge reduction resulted in significantly lower S th values ( Figures 3a and 3b); the helix of PTFE is well ascertained in FT PTFE. 30,31 Each linear molecule orients nearly parallel to the PTFE chains that are stabilized normally with a resulting helix; they are trapped on the negatively charged grooves (Figure 1c) as shown in Figures 4a and 4b: S in values increased and approached a high level with some fluctuation (Figure 4c). In contrast, with the intentionally stabilized model with no helix (Figure 1b), it does not orient to the PTFE chains, and S in fluctuation is so wide that a constant level was not easily found (Figure 4d).…”

mentioning

confidence: 96%

Poly(tetrafluoroethylene) is Unique for Orienting Molecules

Tanaka

Ishitobi

2018

Chem. Lett.

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A physical insight regarding poly(tetrafluoroethylene) (PTFE) is revealed herein. The driving force for the oriented growth of materials on aligned PTFE is investigated. The growth has been reported in numerous publications for a wide range of deposited materials on aligned PTFE layers since its discovery in 1991 because it is a promising method for preparing ordered molecular films. MD model simulations demonstrate herein that the shallow charged atomic grooves between adjacent PTFE chains trap typical two linear molecules, thus explaining the remarkable degrees of uniaxial orientation in their deposited thin films on the layers. Charge modifications to the model demonstrate for the first time that the negative charge of its fluorine atoms is crucial for the remarkable degrees. Hence, such an orientation is only possible with PTFE. Poly(tetrafluoroethylene) (PTFE) is regarded as the king of specialty plastic since its accidental discovery in 1938 by Plunkett.1 Currently, approximately 10 5 tons of PTFE is produced every year.2 Although this amount does account not for 1% of whole synthetic plastic, PTFE plays an irreplaceable role in various applications ranging from non-stick frying pans for kitchens to the chamber lining for corrosive uranium hexafluoride.2 Without PTFE, two atomic bombs would not have exploded in Japan. The outstanding character of PTFE is attributable to its robust CF bonds, which render PTFE extremely inert. 3The first author was specifically interested by a letter 4 and we have been keeping this first interest for over two decades. The oriented growth on PTFE was reported there and it is a promising method for preparing ordered molecular films; highly aligned PTFE thin layers are prepared by friction-transfer (FT) (or a rubbing procedure found later by us), 5 and the materials are merely deposited on the layers. Furthermore, linear molecules such as 1 (Figure 1) nanotubes, 25 and nanocomposites 26 ). For applying their thin films to molecular devices, such orientation is needed to enhance their functions such as carrier mobility 13,2729 and nonlinear optical properties. 7,12 Moreover, an intrinsic query has been nourishing our interest for so long. It remains unknown why this remarkable orientation takes place on extremely inert PTFE layers, e.g., nonsticking and poor wetting materials. An interesting question is: what happens between the orienting molecules and inert PTFE?Linear molecules orient along the atomic grooves between adjacent PTFE chains. We demonstrated previously through an MD simulation that the atomic grooves align some linear molecules including 1 (Figure 1) by trapping them along the grooves. 11The direction of linear molecules should be thus oriented in their early nuclei on which the growth further takes place somewhat epitaxially. Such grooves are shown in Figures 1a1c. However, it has been an open question whether the strong negative charge of F also contributes to trapping on the grooves or not. We report herein such a contribution for the first time.If this atomi...

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Chain Reorientation in Poly(tetrafluoroethylene) by Mobile Twin-Helix Reversal Defects

Cited by 71 publications

References 14 publications

An Alternative Route Towards Metal–Polymer Hybrid Materials Prepared by Vapor‐Phase Processing

An Alternative Route Towards Metal–Polymer Hybrid Materials Prepared by Vapor‐Phase Processing

In-situ Measurement of Crystalline Lattice Strains in Polytetrafluoroethylene

Poly(tetrafluoroethylene) is Unique for Orienting Molecules

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