COMPONENT INTERACTIONS AND THE STABILITY OF SOME PIGMENT POLYMER DISPERSIONS/

The sedimentation behavior of rutile and selected organic pigments dis p ersed in polymer solutions has been interpreted in terms of acid-bas e interactions at the polymer/pigment interface. The acid-base informa tion was obtained from inverse gas chromatography. Moderate strengths of acid-base interaction were beneficial to the stability of dispersio ns, whereas both the absence of and excessive interaction resulted in the rapid deposition of solids. The effect is associated with the orie ntation of adsorbed polymer molecules, which must provide an adequate steric (entropic) barrier for the aggregation and deposition of solids . Implicated is the balance of interaction forces at pigment/polymer a nd polymer/solvent contacts. Rheological data for the dispersions have been used to obtain a parameter related to the thickness of the adsor bed polymer layer, by way of amplifying on the state of the pigment/po lymer interface. (C) 1998 John Wiley & Sons, Inc.