Functional polymers for colloidal applications. II. Hydrophobic effects of polyacrylic copolymer on dispersing polar and nonpolar particles

The polyacrylic acids with fixed molecular weights are specifically esterified by lauryl alcohol and methyl alcohol to prepare copolymers. These copolymers are used as dispersants for dispersing TiO₂ and carbon black. It was found that lauryl‐esterified copolymers decrease the minimum viscosity and optimum concentrations both for TiO₂ and carbon black due to strong hydrophobic interactions. However, the methyl esterified polyacrylic acid significantly broadens the range of optimum concentrations due to the interruption of polymer interactions between particles by methyl groups. Four different dispersion systems (LB/carbon black, LB/TiO₂, MB/carbon black, and MB/TiO₂) are used. These results are discussed and correlated to the structure of dispersant. The bridging effect of esterified lauryl group and the antibridging effect of esterified methyl group are used tó interpre the viscosity phenoma of those dispered systems.