Effectiveness of block copolymers as stabilizers for aqueous titanium dioxide dispersions of a high solid content

Copolymers of 2-(dimethylamino)ethyl methacrylate (DMAEMA) and sodium methacrylate (MANa) have been synthesized and tested as dispersants for the aqueous dispersion of titanium dioxide (80 wt.% solid). The molecular composition of the block copolymers has an effect on the dispersion stability. Triblock copolymers consisting of PMANa outer blocks are unable to stabilize the dispersion. Triblock copolymers of the reverse structure form poorly stable dispersions due to at least partial particle bridging. In the case of non-blocky distribution of the DMAEMA and MANa comonomers in the chains, the stabilization capability is lost. A decrease in the anchoring strength of the diblocks has a deleterious effect on the dispersion stability. Finally, the surface coverage depends on the availability of free copolymer chains (unimers) coexisting with micelles. These trends have been confirmed in a fully formulated paint containing Cu-phthalocyanine pigment