Carboxylate Modified (CML)
Type ID: 2 (pKa~variable, 5-9) 4%
solids
Carboxylate modified latex products are produced by copolymerizing carboxylic acid containing polymers. The result is a latex polymer particle with a highly charged, relatively hydrophilic and somewhat 'fluffy' surface layer. The charge density of the CML particles ranges from about 10 Å2 to 100Å2 per charged group. They are electrosterically stabilized, and are therefore safe in concentrations of electrolyte up to 1M univalent salt. CML modified latex particles are negatively charged with a surface which has a polyelectrolyte character. It is only when the pH is ~10 that all the carboxyl groups are ionized.
For large biomolecules, only the outermost groups are accessible, while a large portion of the carboxyl groups is “buried” underneath and only accessible to small inorganic ions. Therefore the µeq/g data by titration can only be used as a reference to represent the maximum potential of reactive carboxyl groups. An area occupied by each carboxyl group on the outer surface can not be obtained from the titration data.This is a hydrophilic latex.
