HIGHLY HYDROPHOBICALLY-MODIFIED POLYELECTROLYTES - FIELD VARIABLES TOCONTROL EMULSION-TYPE

Highly hydrophobically modified (with n-dodecylamide chain) linear pol y(acrylic acid)s (HHMPAAH) and poly(sodium acrylate)s (HHMPAANa) with various degrees of grafting (tau) were synthesized and used as emulsif iers of the n-dodecane/water system. The type of emulsion, oil in wate r (O/W) or water in oil (W/O), was investigated as a function of the p olymer chemical structure (tau, salt or acid form of the copolymer) an d aqueous phase electrolyte concentration (NaNO3). Increasing tau and/ or salt concentration was found to favor the formation of inverse emul sions. Direct liquid-liquid dispersions are more likely to form with p oly(sodium acrylate)s than with poly(acrylic acid)s. Hence, field vari ables such as tau, pH and ionic strength are relevant parameters to co ntrol emulsion type. Moreover, a balanced polyelectrolyte neither solu ble in oil nor in water was synthesized for the first time. With this original emulsifier, the dispersion type was found to change from O/W to W/O with polymer salting out. The work provides convenient model sy stem for fundamental studies of polymer conformation at liquid-liquid interfaces.