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Polyacrylic acid

Poly(acrylic acid)
Polyacrylic acid.png
Names
IUPAC name
Poly(acrylic acid)
Other names
PAA, PAAc, Acrysol, Acumer, Alcosperse, Aquatreat, Carbomer, Sokalan
Identifiers
ChemSpider
  • none
ECHA InfoCard 100.115.375
KEGG
UNII
Properties
(C3H4O2)n
Molar mass variable
Hazards
Irritant Xi
R-phrases (outdated) R36 R37 R38
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g., sodium chloride Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YesYN ?)
Infobox references

Poly(acrylic acid) (PAA or Carbomer) is generic name for synthetic high molecular weight polymers of acrylic acid. They may be homopolymers of acrylic acid, crosslinked with an allyl ether pentaerythritol, allyl ether of sucrose or allyl ether of propylene. In a water solution at neutral pH, PAA is an anionic polymer, i.e. many of the side chains of PAA will lose their protons and acquire a negative charge. This makes PAAs polyelectrolytes, with the ability to absorb and retain water and swell to many times their original volume. Dry PAAs are found in the market as white and fluffy powders. 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.

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. In aqueous solutions PAA can also form polycomplexes with oppositely charged polymers (for example, chitosan), surfactants and drug molecules (for example, streptomycin).

Polyacrylic acid and its derivatives are used in disposable diapers, ion exchange resins and adhesives. They are also popular as thickening, dispersing, suspending and emulsifying agents in pharmaceuticals, cosmetics and paints. PAA may inactivate the antiseptic chlorhexidine gluconate. The neutralized polyacrylic acid gels are suitable to obtain biocompatible matrices for medical applications such as gels for skin care or skin disease treatment products. For the development of polymeric matrices which allows controlled delivery rate of active substances, the recent investigations aimed towards the clarification of the conformational changes of the polymeric gel during neutralization, light irradiation and embedment of gold nanoparticles.


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