Polyacrylic acid
Names | |
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IUPAC name
Poly(acrylic acid), poly(1-carboxyethylene)
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Other names
PAA, PAAc, Acrysol, Acumer, Alcosperse, Aquatreat, Carbomer, Sokalan
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Identifiers | |
ChEBI | |
ChemSpider |
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ECHA InfoCard
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100.115.375 |
EC Number |
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KEGG | |
UNII |
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CompTox Dashboard (EPA)
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Properties | |
(C3H4O2)n | |
Molar mass | variable |
log P | 0.25700[1] |
Hazards[2] | |
GHS labelling: | |
Warning | |
H315, H319, H335 | |
NFPA 704 (fire diamond) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Poly(acrylic acid) (PAA; trade name Carbomer) is a
Synthesis
PAA, like any acrylate polymer, is usually synthesized through a process known as free radical polymerization,[3][4] though graft polymerization may also be used.[5][6] Free radical polymerization involves the conversion of monomers, in this case, acrylic acid (CH2=CHCO2H), into a polymer chain through the action of free radicals.[7][8][9] The process typically follows these steps:[10]
- Initiation: Free radicals are generated by initiators such as potassium persulfate (K2S2O8) or Azobisisobutyronitrile (AIBN). These radicals are highly reactive and can start the polymerization process by reacting with the monomer units.[11]
- Propagation: Once the radical reacts with a monomer, it creates a new radical at the end of the growing chain. This new radical can react with additional monomer units, allowing the chain to grow.[12]
- Termination: The reaction continues until two radicals recombine, or a radical is transferred to another molecule, terminating the growth of the polymer chain.[13]
- Chain transfer and inhibition: Other reactions can also occur, such as chain transfer (where the radical is transferred to a different molecule, creating a new radical) or inhibition (where impurities stop the growth of the chain).[14]
Production
The global market is estimated to be worth $3.4 billion in 2022.[15][16]
Structure and derivatives
Polyacrylic acid is a weak anionic polyelectrolyte, whose degree of ionisation is dependent on solution pH. In its non-ionised form at low pHs, PAA may associate with various non-ionic polymers (such as polyethylene oxide, poly-N-vinyl pyrrolidone, polyacrylamide, and some cellulose ethers) and form hydrogen-bonded interpolymer complexes.[17] In aqueous solutions PAA can also form polycomplexes with oppositely charged polymers such as chitosan, surfactants, and drug molecules (for example, streptomycin).[18]
Physical properties
Dry PAAs are sold as white, fluffy powders.
Derivatives
In the dry powder form of
Applications
Absorbent
PAA is widely used in dispersants. Its molecular weight has a significant impact on the rheological properties and dispersion capacity, and hence applications. The dominant application for PAA is as a superabsorbent. About 25% of PAA is used for detergents and dispersants.
Polyacrylic acid and its derivatives (particularly
Cleaning
Detergents often contain copolymers of acrylic acid that assist in sequestering dirt. Cross-linked polyacrylic acid has also been used in the production of household products, including floor cleaners. PAA may inactivate the
Biocompatible materials
The neutralized polyacrylic acid gels are suitable biocompatible matrices for medical applications such as gels for skin care products. PAA films can be deposited on orthopaedic implants to protect them from corrosion. Crosslinked hydrogels of PAA and gelatin have also been used as medical glue.
Paints and cosmetics
Other applications involve paints and cosmetics. They stabilize suspended solid in liquids,[22] prevent emulsions from separating, and control the consistency in flow of cosmetics. Carbomer codes (910, 934, 940, 941, and 934P) are an indication of molecular weight and the specific components of the polymer. For many applications PAAs are used in form of alkali metal or ammonium salts, e.g. sodium polyacrylate.
Emerging applications
Hydrogels derived from PAA have attracted much study for use as bandages and aids for wound healing.[23]
Drilling fluid and metal quenching
A few reports were made on PAA use as deflocculant (so called alkaline polyacrylates) for oil drilling industry.[24][25]
It was also reported to be used for metal quenching in metalworking (see Sodium polyacrylate).[26]
References
- ^ "Polyacrylic acid_msds". Archived from the original on 2022-02-21. Retrieved 2018-04-23.
- ^ "C&L Inventory". echa.europa.eu. Archived from the original on 2021-04-05. Retrieved 2021-12-05.
- S2CID 93458743.
- PMID 12102191.
- ISSN 0021-8995.
- ISSN 1022-1336.
- ISSN 0024-9297.
- ISBN 978-0-8412-2905-1, retrieved 2023-12-20
- S2CID 139704996, retrieved 2023-12-20
- S2CID 225117544.
- ISSN 1022-1352.
- ISSN 0021-8995.
- S2CID 257729740.
- ISSN 0888-5885.
- ^ "Polyacrylic Acid Market Demand, Key Players, Opportunities, & Forecast Analysis By 2029". www.databridgemarketresearch.com. Retrieved 2023-12-20.
- ^ ltd, Research and Markets. "Polyacrylic Acid - Global Strategic Business Report". www.researchandmarkets.com. Retrieved 2023-12-20.
- OCLC 1200871469. Archivedfrom the original on 2022-02-21. Retrieved 2022-02-21.
- from the original on 21 February 2022 – via PubMed, Elsevier.
- from the original on 2022-02-21. Retrieved 2022-02-21.
- ^ "Acrylates". The Macrogalleria. Polymer Science Learning Center. 2005. Archived from the original on 21 February 2022. Retrieved 25 June 2015.
- from the original on 19 December 2021 – via PubMed, Elsevier.
- ISSN 0021-8995.
- from the original on 1 February 2022.
- ^ "Deflocculants: A Detailed Overview". Archived from the original on February 26, 2021.
- doi:10.17122/ogbus-2017-6-6-19 (inactive 2024-02-01).)
{{cite journal}}
: CS1 maint: DOI inactive as of February 2024 (link - ^ Griffiths, W. D. (1989). The quenching characteristics of sodium polyacrylate solutions (doctoral thesis). Sheffield: Sheffield Hallam University.