Polycarboxylates are linear polymers with a high molecular mass (M_r ≤ 100 000) and with many carboxylate groups. They are polymers of acrylic acid or copolymers of

acrylic acid Acrylic acid (IUPAC: propenoic acid) is an organic compound with the formula CH2=CHCOOH. It is the simplest unsaturated carboxylic acid, consisting of a vinyl group connected directly to a carboxylic acid terminus. This colorless liquid has a ...

and maleic acid. The polymer is used as the sodium salt (see: sodium polyacrylate).

Use

Polycarboxylates are used as builders in detergents. Their high chelating power, even at low concentrations, reduces deposits on the laundry and inhibits the crystal growth of

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

. Polycarboxylate ethers (PCE) are used as superplasticizers in concrete production.

Safety

Polycarboxylates are poorly

biodegradable Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegradati ...

but have a low ecotoxicity. In the sewage treatment plant, the polymer remains largely in the sludge and is separated from the wastewater. Polyamino acids like polyaspartic acid and polyglutamic acid have better biodegradability but lower chelating performance than polyacrylates. They are also less stable towards heat and alkali. Since they contain nitrogen, they contribute to eutrophication.

References

{{reflist Polymers Salts and esters of carboxylic acids