Abstract:Hydrophobically-modified alkali soluble polyacrylic emulsions (HASE) with different amount of methacrylic esters of ethoxylated (25 mol EO) C22(BEM) were synthesized via directly monomer feeding semi-continuous emulsion polymerization. Through the control of NaOH/COOH mole ratio R, effects of R on pH, light transmittance, viscosity, solubility of particle SP, apparent dissociation constant pKa and η0, η∞, [η] were investigated. The results show that the pH is platform-like at the range of R=0.1~0.8, the starting point of HASE phase transition from hard spherical latex particle to solution is R≈0.4, and the end point is R≈0.8 with the corresponding pH of 7. The more amount of BEM content, the greater proton transfer Gibbs energy ΔGel, the higher R value of phase transition is. The curves of η0 and η∞ show two slopes at R approximately 0.8, while [η] only a slope. η0, η∞ and [η] exhibit sensitive to pH. With the increase of pH and BEM content, the viscosity coefficient K firstly increases and then decreases, and the flow index n firstly decreases and then increases.