Water dispersible polyester resins derived from dimethyl terephthalate, dimethyl 5-sulfoisophthalate sodium salt, 1,2-propane diol and diethylene glycol were prepared. A
Design of Experiment (DOE) was explored by varying the concentration of the ionic 5-sulfo-isophthalate sodium salt and diethylene glycol at various molecular weights and found to
correlate with particle size dispersion of the sulfonated resins in water. An empirical model for the resin glass transition was also obtained through experimental design.