Polyvinylidene fluoride

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Structural formula
Structure of polyvinylidene fluoride
General
Surname Polyvinylidene fluoride
other names

PVDF

CAS number 24937-79-9
Monomer Vinylidene fluoride
Molecular formula of the repeating unit C 2 H 2 F 2
Molar mass of the repeating unit 64.03 g mol −1
Type of polymer

Thermoplastic

properties
Physical state

firmly

density

1.76-1.78 g · cm −3

Melting point

175 ° C

Crystallinity

partially crystalline

modulus of elasticity

2100 N mm −2 (tension)

Water absorption

0.03-0.04%

Thermal conductivity

0.2 W / (m K)

Thermal expansion coefficient

14 · 10 −5 K −1

safety instructions
GHS labeling of hazardous substances
no classification available
H and P phrases H: see above
P: see above
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Polyvinylidene fluoride (also known as polyvinylidene difluoride , abbreviation PVDF ) is an opaque , partially crystalline, thermoplastic fluoroplastic .

Manufacturing

The basic materials for PVDF are hydrogen fluoride and methyl chloroform , which are converted to chlorodifluoroethane and then to vinylidene fluoride . Vinylidene fluoride is then polymerized to polyvinylidene fluoride in ultrapure water under controlled pressure and temperature conditions using a catalyst .

history

PVDF was marketed under the brand name "Kynar" in 1961 by Pennwalt Corporation . In 1969, Kawai discovered the piezoelectric effect of PVDF. Two years later, Nakamura and Wada also observed ferroelectric properties in PVDF.

use

Because of its good thermal and chemical resistance , PVDF is used as a lining for pipes or external components. It is also used for seals , membranes and packaging films. It is also used in measurement technology, e.g. B. when coating measuring probes. Since the material shows strong piezoelectric effects compared to other polymers after appropriate polarization , it is used in microphones , hydrophones , loudspeakers and actuators . It is also to be tested for variable mirrors in space technology. In microelectronics, the ferroelectric properties of PVDF could be used for computer memories in the future.

In the life sciences , PVDF is used as a carrier membrane for Western blotting . Compared to nitrocellulose , PVDF membranes are more expensive, but they are also more stable and allow multiple use ( reprobing ). Another area of ​​application is medical technology , where PVDF can be used as a prosthesis material or for the production of so-called meshes for (preperitoneal) mesh plastic in the surgical treatment of hernias

Since it can be produced with high purity, it is used, for example, in chip production for pipeline systems for the transport of high-purity media such as ultrapure water .

PVDF is also widely used in membrane technology (for example in bacterial filters that are required for sterile filtering of solutions in biochemistry). The chemical resistance is used, which allows the material to withstand more intensive chemical cleaning than some other membrane materials. However, the hydrophobic properties of PVDF are a disadvantage in terms of filtration .

In powder form, the polymer is also used as a binding material in the electrodes of lithium-ion batteries .

Fishing line is made from PVDF filament (cord) , as well as strings for plucked instruments such as ukulele, guitar and harp.

Manufacturer and trade name

Individual evidence

  1. ↑ a b c d e f Technical data sheet PVDF (PDF; 22 kB), Amsler & Frey AG, accessed on April 4, 2013.
  2. ↑ Data sheet polyvinylidene fluoride (PVDF) , Kern GmbH, accessed on April 4, 2013.
  3. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
  4. ^ Heiji Kawai: The Piezoelectricity of Poly (vinylidene fluoride) . In: Japanese Journal of Applied Physics . tape 8 , no. 7 , July 1969, p. 975-976 , doi : 10.1143 / JJAP.8.975 .
  5. ↑ Ken'ichi Nakamura, Yasaku Wada: Piezoelectricity, pyroelectricity, and the electrostriction constant of poly (vinylidene fluoride) . In: Journal of Polymer Science Part A -2: Polymer Physics . tape 9 , no. 1 , January 1971, p. 161–173 , doi : 10.1002 / pol . 1971.160090111 .
  6. ^ RCG Naber et al .: Organic Nonvolatile Memory Devices Based on Ferroelectricity. In: Advanced Materials . (2009), 22, 945, doi : 10.1002 / adma.200900759 .
  7. ↑ Stéphanie Houis, Felixine Siegmund, Marijan Barlé, Thomas Gries: Bioresorbable textiles for medical applications. In: Technical textiles. 4/2007, p. 294 f.
  8. ↑ Karsten Junge, Jens Otto, Hasan Oral: Clinical snapshot: Rare cause of a gastric outlet obstruction - the scrotal hernia. In: Deutsches Ärzteblatt. Volume 116, Issue 29 f., (July 22) 2019, p. 507.
  9. ↑ David Linden, Thomas B. Reddy (Ed.): Linden's Handbook of Batteries . Third edition. Mcgraw-Hill, 2002, ISBN 978-0-07-135978-8 .

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