Partitioning of monobutyl itaconate and β-carboxyethyl acrylate between organic and water phases

ABSTRACT Unsaturated carboxylic acids are usually used as functional monomers at low concentrations in emulsion polymerization to improve the colloidal stability and the mechanical properties of the films prepared from the corresponding latexes. These acids are distributed between the aqueous and organic phases to different extents due to their various water solubilities. The partitioning behavior of two new vinyl acids, monobutyl itaconate (MBI) and β‐carboxyethyl acrylate (β‐CEA), between n‐butyl methacrylate (BMA) and the water phases was studied in this work. In addition, the partitioning of commonly used acrylic acid (AA) and methacrylic acid (MAA) was also determined as a benchmark. It was found that the partition coefficients (D) of MBI and β‐CEA depended to a large extent on the acid concentration in the total comonomer mixture; the same trends were observed for AA and MAA. With the variation in monomer to water ratio (M/W), the D value of lipophilic acid MBI changed significantly, while for hydrophilic acid β‐CEA, the D value changed very little. Furthermore, the values of the partition coefficient of MBI and β‐CEA were very strong functions of pH, decreasing rapidly as the pH is increased. On the other hand, temperature has little effect on the partition coefficients for vinyl acids under typical emulsion polymerization reaction conditions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40868.