ABSTRACT
This chapter will cover the key elements which have to be considered when trying to understand the use of polymers in detergent. The polymers which will be discussed are those entering in the composition of multicomponent builder systems; that is, those which provide performance benefits in areas such as sequestration of positively charged ions, crystal inhibition and distortion, and suspension and dispersion of insoluble matters. To effectively function in these performance areas, the polymers need to have some "active sites"; that is, some groups along the backbone chain which can be ionized and then interact with ions and surfaces. We will, therefore, discuss in this chapter those polymers containing negatively charged groups, and more specifically polycarboxylated polymers. All of those polymers can be described by the following structure:
Z COOH
The structure with the lowest carboxylate density in the schema above will be when all X, Y, and Z are hydrogens and the shown monomer acrylic acid:
(-CH2-~H-) COOH n
It would, however, be a mistake to conclude that a homopolyacrylate polymer would be the lowest density charge polymer producible. In fact, it is possible to copolymerize uncharged monomers within the sequence of the acrylic acid monomers and actually obtain a polymeric chain of a total charge density inferior to the homopolyacrylate chain. For instance, by copolymerizing ethylene monomers in the acrylate chain, one can get to a polymeric structure having the following structure:
( -CH2-CH-) I (-CHz-CHz-)m COOH n
560 Zini
This polymer will interact with positively charged ions to a much lesser extent than the polyacrylate described earlier; by "diluting" the acrylate monomers more and more with noncharged ethylene monomers, we can gradually reduce the interaction of the copolymer with the ions.
