Fluorotelomer
Encyclopedia
Fluorotelomers are fluorocarbon
-based oligomers, or telomer
s, synthesized by telomerization
. Some fluorotelomers and fluorotelomer-based compounds
are a source of environmentally persistent perfluorinated carboxylic acid
s such as PFOA
and PFNA
, while others are under extended investigation.
telomerization of fluorotelomer molecule
s, a variety of fluorinated alkenes can serve as unsaturated
taxogens including tetrafluoroethylene
, vinylidene fluoride, chlorotrifluoroethylene
, and hexafluoropropene. However, many fluorotelomers, such as fluorotelomer alcohol
s, are fluorocarbon
-based because they are synthesized from tetrafluoroethylene. In addition to alcohols, synthetic products include fluorotelomer iodides, olefins, and acrylate
monomer
. Polymer
ized acrylate from iodide and alcohol monomers represent >80% of the global manufacture and use of fluorotelomer-based products.
Fluorotelomers are used in "fire-fighting foams, grease-resistant food packaging, leather protectants and stain-resistant carpeting and textiles." Fluorotelomers are applied to food contact papers for their lipophobicity
, making paper resistant to absorbing oil
from fatty foods. Fluorotelomer coatings are used in microwave popcorn bags, fast food wrappers, candy wrappers, and pizza box liners.
PFOA is also formed as an unintended byproduct in the production of fluorotelomers, and is thus present in finished goods treated with fluorotelomers, including those intended for food contact. In an U.S. Food and Drug Administration (USFDA) study, fluorotelomer-based paper coatings (which can be applied to food contact paper in the concentration range of 0.4%) were found to contain 88,000–160,000 parts per billion PFOA, while microwave popcorn bags
contained 6–290 parts per billion PFOA.
After more than a year of negotiating with "telomer
makers Asahi Glass, Clariant, Daikin America, and DuPont to perform degradation studies on 13 of their products", the U.S. Environmental Protection Agency (USEPA) and companies were not able to agree on terms. Thus, in late June 2004 the USEPA announced it would it perform the degradation studies itself, with an expected time to complete the studies of 1 year. However, in a December 2005 deal with the USEPA over alleged withholdings, DuPont agreed to test nine of its fluorotelomer-based products' potential to break down into PFOA by 27 December 2008. Yet, in late December 2008, the USEPA and DuPont filed a joint motion stating that DuPont needed additional time to purify the products. USEPA lawyers extended the deadline by three years, to 27 December 2011, in the last month of the Bush Administration.
In 2009 a 546 day USEPA study was published that estimated a degradation half-life for a fluorotelomer-based polymer in the range of 10–17 years. This estimate is shorter than the half-life estimated by a DuPont study.
Fluorocarbon
Fluorocarbons, sometimes referred to as perfluorocarbons or PFCs, are organofluorine compounds that contain only carbon and fluorine bonded together in strong carbon–fluorine bonds. Fluoroalkanes that contain only single bonds are more chemically and thermally stable than alkanes...
-based oligomers, or telomer
Telomer
The word telomer has two distinct, yet related meanings.*Its original meaning is in polymer science, when telomerization results in an extremely small polymer—one whose degree of polymerization is generally between 2 and 5....
s, synthesized by telomerization
Telomerization
Telomerization is a radical polymerization reaction where a chain transfer limits the size of the oligomer molecule product—the telomer. Telomerization requires a telogen to react with at least one unsaturated taxogen molecule. Fluorotelomers are an example.-See also:*Perfluorooctanoic acid...
. Some fluorotelomers and fluorotelomer-based compounds
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
are a source of environmentally persistent perfluorinated carboxylic acid
Perfluorinated carboxylic acid
Perfluorinated carboxylic acids , or perfluorocarboxylates are fully fluorinated organofluorine compounds—or perfluorinated compounds—with carboxylic acid or carboxylate functional groups. PFCAs are fluorocarbon derivatives...
s such as PFOA
Perfluorooctanoic acid
Perfluorooctanoic acid , also known as C8 and perfluorooctanoate, is a synthetic, stable perfluorinated carboxylic acid and fluorosurfactant. One industrial application is as a surfactant in the emulsion polymerization of fluoropolymers. It has been used in the manufacture of such prominent...
and PFNA
Perfluorononanoic acid
Perfluorononanoic acid, or PFNA, is a synthetic perfluorinated carboxylic acid and fluorosurfactant that is also an environmental contaminant found in people and wildlife along with PFOS and PFOA.-Chemistry and properties:...
, while others are under extended investigation.
Manufacture and use
In the radicalRadical (chemistry)
Radicals are atoms, molecules, or ions with unpaired electrons on an open shell configuration. Free radicals may have positive, negative, or zero charge...
telomerization of fluorotelomer molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
s, a variety of fluorinated alkenes can serve as unsaturated
Saturation (chemistry)
In chemistry, saturation has six different meanings, all based on reaching a maximum capacity...
taxogens including tetrafluoroethylene
Tetrafluoroethylene
Tetrafluoroethylene is a chemical compound with the formula C2F4. It is the simplest alkene fluorocarbon. This gaseous species is used primarily in the industrial preparation of polymers.-Properties:...
, vinylidene fluoride, chlorotrifluoroethylene
Chlorotrifluoroethylene
CTFE, or chlorotrifluoroethylene is a chlorofluorocarbon with chemical formula CF2CClF. It is commonly used as a refrigerant in cryogenic applications. CTFE can be polymerised to produce the plastic ECTFE....
, and hexafluoropropene. However, many fluorotelomers, such as fluorotelomer alcohol
Fluorotelomer alcohol
Fluorotelomer alcohols, or FTOHs, are fluorotelomers with an alcohol functional group. They are volatile precursors to perfluorinated carboxylic acids, such as PFOA and PFNA, and other compounds.-Naming:...
s, are fluorocarbon
Fluorocarbon
Fluorocarbons, sometimes referred to as perfluorocarbons or PFCs, are organofluorine compounds that contain only carbon and fluorine bonded together in strong carbon–fluorine bonds. Fluoroalkanes that contain only single bonds are more chemically and thermally stable than alkanes...
-based because they are synthesized from tetrafluoroethylene. In addition to alcohols, synthetic products include fluorotelomer iodides, olefins, and acrylate
Acrylate
The acrylate ion is the ion of acrylic acid.Acrylates are the salts and esters of acrylic acid. They are also known as propenoates ....
monomer
Monomer
A monomer is an atom or a small molecule that may bind chemically to other monomers to form a polymer; the term "monomeric protein" may also be used to describe one of the proteins making up a multiprotein complex...
. Polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
ized acrylate from iodide and alcohol monomers represent >80% of the global manufacture and use of fluorotelomer-based products.
Fluorotelomers are used in "fire-fighting foams, grease-resistant food packaging, leather protectants and stain-resistant carpeting and textiles." Fluorotelomers are applied to food contact papers for their lipophobicity
Lipophobicity
Lipophobicity, also sometimes called lipophobia, is a chemical property of chemical compounds which means "fat rejection", literally "fear of fat". Lipophobic compounds are those not soluble in lipids or other non-polar solvents...
, making paper resistant to absorbing oil
Oil
An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....
from fatty foods. Fluorotelomer coatings are used in microwave popcorn bags, fast food wrappers, candy wrappers, and pizza box liners.
Environmental and health concerns
Some fluorotelomers can be metabolized into PFOA, a persistent global contaminant found in people in the low-parts per billion range. Toxicologists estimate microwave popcorn, because of the high heat and coated bag, could account for about 20% of the PFOA levels measured in an individual consuming 10 bags a year if 1% of the fluorotelomers are metabolized to PFOA.PFOA is also formed as an unintended byproduct in the production of fluorotelomers, and is thus present in finished goods treated with fluorotelomers, including those intended for food contact. In an U.S. Food and Drug Administration (USFDA) study, fluorotelomer-based paper coatings (which can be applied to food contact paper in the concentration range of 0.4%) were found to contain 88,000–160,000 parts per billion PFOA, while microwave popcorn bags
Popcorn bag
A microwave popcorn bag is an engineered, enhanced, sealed paper bag in which un-popped popcorn is sold for the purpose of cooking popcorn in a microwave oven. These bags and their contents are sometimes referred to as microwave popcorn...
contained 6–290 parts per billion PFOA.
Industry and government actions
In 2002 Burger King stopped using fluorotelomer coated boxes.After more than a year of negotiating with "telomer
Telomer
The word telomer has two distinct, yet related meanings.*Its original meaning is in polymer science, when telomerization results in an extremely small polymer—one whose degree of polymerization is generally between 2 and 5....
makers Asahi Glass, Clariant, Daikin America, and DuPont to perform degradation studies on 13 of their products", the U.S. Environmental Protection Agency (USEPA) and companies were not able to agree on terms. Thus, in late June 2004 the USEPA announced it would it perform the degradation studies itself, with an expected time to complete the studies of 1 year. However, in a December 2005 deal with the USEPA over alleged withholdings, DuPont agreed to test nine of its fluorotelomer-based products' potential to break down into PFOA by 27 December 2008. Yet, in late December 2008, the USEPA and DuPont filed a joint motion stating that DuPont needed additional time to purify the products. USEPA lawyers extended the deadline by three years, to 27 December 2011, in the last month of the Bush Administration.
In 2009 a 546 day USEPA study was published that estimated a degradation half-life for a fluorotelomer-based polymer in the range of 10–17 years. This estimate is shorter than the half-life estimated by a DuPont study.