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Polyacrylamide

Names
IUPAC name poly(2-propenamide)
Identifiers
CAS Number	9003-05-8
ChemSpider	none
ECHA InfoCard	100.118.050
UNII	5D6TC4BRWV (1500 MW)
CompTox Dashboard (EPA)	DTXSID7042308
Properties
Chemical formula	(C3H5NO)n
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). N verify (what is  ?) Infobox references

Polyacrylamide (IUPAC poly(2-propenamide) or poly(1-carbamoylethylene), abbreviated as PAM) is a polymer (-CH₂CHCONH₂-) formed from acrylamide subunits. It can be synthesized as a simple linear-chain structure or cross-linked, typically using N,N'-methylenebisacrylamide. In the cross-linked form, the possibility of the monomer being present is reduced even further. It is highly water-absorbent, forming a soft gel when hydrated, used in such applications as polyacrylamide gel electrophoresis, and can also be called ghost crystals when cross-linked, and in manufacturing soft contact lenses. In the straight-chain form, it is also used as a thickener and suspending agent. In 2008, an estimated 750,000,000 kg were produced.

Physicochemical properties

Linear polyacrylamide is a water-soluble. Linear polyacrylamide is a water-soluble polymer. Owing to partial hydrolysis, some amide substituents convert to carboxylates. This hydrolysis thus makes the polymer particularly hydrophilic.

Polyacrylamide is a polyolefin. It can be viewed as polyethylene with amide substituents on alternating carbons. Unlike various nylons, polyacrylamide is not a polyamide because the amide group is not in the polymer backbone.

Uses

37% for watertreatment (primarily flocculants, 22% formunicipal and 15% for industrial water treat-ment), 25% for additives in pulp and paper,20% for oil recovery, 10% for mineral process-ing, , and 8% other.

In the 1970s and 1980s, the proportionately largest use of these polymers was in water treatment. The next major application by weight is additives for pulp processing and papermaking. 30% of polyacrylamide is used in the oil and mineral industries.

Flocculation

One of the largest uses for polyacrylamide is to flocculate solids in a liquid. This process applies to water treatment, and processes like paper making and screen printing. Polyacrylamide can be supplied in a powder or liquid form, with the liquid form being subcategorized as solution and emulsion polymer.

Even though these products are often called 'polyacrylamide', many are actually copolymers of acrylamide and one or more other species, such as an acrylic acid or a salt thereof. These copolymers have modified wetting and swellability.

The ionic forms of polyacrylamide has found an important role in the potable water treatment industry. Trivalent metal salts, like ferric chloride and aluminum chloride, are bridged by the long polymer chains of polyacrylamide. This results in significant enhancement of the flocculation rate. This allows water treatment plants to greatly improve the removal of total organic content (TOC) from raw water.

Enhanced oil recovery

In oil and gas industry Polyacrylamide derivatives especially co-polymers of that have a substantial effect on unconventional production and hydraulic fracturing. Polyacrylamide and its derivatives is in subsurface applications such as Enhanced Oil Recovery. High viscosity aqueous solutions can be generated with low concentrations of polyacrylamide polymers, and these can be injected to improve the economics of conventional waterflooding.

Soil conditioning

The primary functions of polyacrylamide soil conditioners are to increase soil tilth, aeration, and porosity and reduce compaction, dustiness and water run-off. Secondary functions are to increase plant vigor, color, appearance, rooting depth and emergence of seeds while decreasing water requirements, diseases, erosion and maintenance expenses. FC 2712 is used for this purpose.

Niche

The polymer is also used to make Gro-Beast toys, which expand when placed in water, such as the Test Tube Aliens. Similarly, the absorbent properties of one of its copolymers can be utilized as an additive in body-powder.

It has been used in Botox as a subdermal filler for aesthetic facial surgery (see Aquamid).

It was also used in the synthesis of the first Boger fluid.

Molecular biology laboratories

Polyacrylamide is also often used in molecular biology applications as a medium for electrophoresis of proteins and nucleic acids in a technique known as PAGE.

Polyacrylamide was first used in a laboratory setting in the early 1950s. In 1959, the groups of Davis and Ornstein and of Raymond and Weintraub independently published on the use of polyacrylamide gel electrophoresis to separate charged molecules. The technique is widely accepted today, and remains a common protocol in molecular biology labs.

Acrylamide has other uses in molecular biology laboratories, including the use of linear polyacrylamide (LPA) as a carrier, which aids in the precipitation of small amounts of DNA. Many laboratory supply companies sell LPA for this use.

Environmental effects

Because of the volume of polyacrylamide produced, these materials have been heavily scrutinized. polyacrylamide is of low toxicity but its precursor acylamide is hazardous. Thus, concerns often center on the possibility that polyacrylamide is contaminated with acrylamide, a known neurotoxin and carcinogen.

Additionally, there are concerns that polyacrylamide may de-polymerise to form acrylamide. In a study conducted in 2003 at the Central Science Laboratory in Sand Hutton, England, polyacrylamide was treated similarly as food during cooking. It was shown that these conditions do not cause polyacrylamide to de-polymerise significantly.

In a study conducted in 1997 at Kansas State University, the effect of environmental conditions on polyacrylamide were tested, and it was shown that degradation of polyacrylamide under certain conditions can cause the release of acrylamide. The experimental design of this study as well as its results and their interpretation have been questioned, and a 1999 study by the Nalco Chemical Company did not replicate the results.

See also

• Aquamid
• Chitosan
• Rhoca-Gil
• Sodium polyacrylate, a similar material

References

1. Herth, Gregor; Schornick, Gunnar; l. Buchholz, Fredric (2015). "Polyacrylamides and Poly(Acrylic Acids)". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. pp. 1–16. doi:10.1002/14356007.a21_143.pub2. ISBN 978-3-527-30673-2.
2. "Polyacrylamide". Hazardous Substances Data Bank. United States National Library of Medicine. February 14, 2003. Consumption Patterns. CASRN: 9003-05-8. Retrieved November 30, 2013.
3. Davis and Ornstein Archived 2011-09-26 at the Wayback Machine. Pipeline.com. Retrieved on 2012-06-11.
4. ^ Reynolds S, Weintraub L (18 September 1959). "Acrylamide Gel as a Supporting Medium for Zone Electrophoresis". Science. 130 (3377): 711. Bibcode:1959Sci...130..711R. doi:10.1126/science.130.3377.711. PMID 14436634. S2CID 7242716.
5. GenElute™-LPA from Sigma-Aldrich. biocompare.com
6. Environment Canada; Health Canada (August 2009). "Screening Assessment for the Challenge: 2-Propenamide (Acrylamide)". Environment and Climate Change Canada. Government of Canada.
7. Dotson, GS (April 2011). "NIOSH skin notation (SK) profile: acrylamide [CAS No. 79-06-1]" (PDF). DHHS (NIOSH) Publication No. 2011-139. National Institute for Occupational Safety and Health (NIOSH).
8. https://www.cdc.gov/niosh/docs/2011-139/pdfs/2011-139.pdf
9. Woodrow JE; Seiber JN; Miller GC. (Apr 23, 2008). "Acrylamide Release Resulting from Sunlight Irradiation of Aqueous Polyacrylamide/Iron Mixtures". Journal of Agricultural and Food Chemistry. 56 (8): 2773–2779. doi:10.1021/jf703677v. PMID 18351736.
10. Ahn JS; Castle L. (5 November 2003). "Tests for the Depolymerization of Polyacrylamides as a Potential Source of Acrylamide in Heated Foods". Journal of Agricultural and Food Chemistry. 51 (23): 6715–6718. doi:10.1021/jf0302308. PMID 14582965.
11. Smith EA; Prues SL; Oehme FW. (June 1997). "Environmental degradation of polyacrylamides. II. Effects of environmental (outdoor) exposure". Ecotoxicology and Environmental Safety. 37 (1): 76–91. doi:10.1006/eesa.1997.1527. PMID 9212339. Archived from the original on 2016-04-20. Retrieved 2007-11-02.
12. Kay-Shoemake JL; Watwood ME; Lentz RD; Sojka RE. (August 1998). "Polyacrylamide as an organic nitrogen source for soil microorganisms with potential effects on inorganic soil nitrogen in agricultural soil". Soil Biology and Biochemistry. 30 (8/9): 1045–1052. doi:10.1016/S0038-0717(97)00250-2.
13. Gao JP; Lin T; Wang W; Yu JG; Yuan SJ; Wang SM. (1999). "Accelerated chemical degradation of polyacrylamide". Macromolecular Symposia. 144: 179–185. doi:10.1002/masy.19991440116. ISSN 1022-1360.
14. Ver Vers LM. (December 1999). "Determination of acrylamide monomer in polyacrylamide degradation studies by high-performance liquid chromatography". Journal of Chromatographic Science. 37 (12): 486–494. doi:10.1093/chromsci/37.12.486. PMID 10615596.

• Gels
• Neurotoxins
• Acrylate polymers
• Polyelectrolytes
• Acrylamides