PHOTOPHYSICAL CHARACTERIZATION OF POLYELECTROLYTES IN THE FORM OF POLYMERIZED MICELLES FROM AN IONIC SURFACTANT WITH A TERMINAL DOUBLE-BOND

A polymerized micelle poly(sodium undecenoate), PSUe, synthesized from an ionic surfactant with a terminal double bond has been studied by photophysical methods in aqueous solution. The data suggest that PSUe undergoes a conformational transition at pH around 8.5. At low pH < 8, the polymer forms a compact hydrophobic structure, at high > 10, the polymer tends to expand to a looser polymerized micelle, quite unlike PA-18K2 and/or PMA. PA-18K2 provides compact host structures for pyrene molecules over the entire pH range, while PMA tends to open in an extended form at pH > 5 and expose pyrene to the aqueous environment. The different pH effects are attributed to the different hydrocarbon side chains linked to the polymer backbone. In polymerized micelles compared to simple ionic sodium undecanoate micelles, USa, the movement of guest molecules is substantially restricted due to the screening effect of the polymer backbone: this occurs even in the looser polymer forms at higher pH. Different methods of synthesis do not lead to polymerized micelles of different structure but to polymers of different molecular weight, with one polymer molecule forming one polymerized micelle in the systems studied. The present studies demonstrate that tailoring of polymers to meet set needs may be achieved by changing the length of the hydrocarbon segment in the monomer surfactant.