Large molecular weight insoluble polyacrylate
polymers are composed of long chains with regularly
distributed carboxylic groups, neutralized by Na+, K+,
or NH4
+. They swell to form gels that contain many
times their weight in water and are used in diapers,
paper towels, and feminine products. It is estimated
that over 130 Gg of polyacrylates are used annually in
such products (Martin 1996). Hydrophilic polymers
are also marketed as “superabsorbent polymers,”
under different trade names, for incorporation into
soils and substrates when an increase in the waterholding
capacity is desirable.