ELECTRICAL CONDUCTIVITY OF HYDROPHOBICALLY MODIFIED POLYELECTROLYTES IN METHANOL/WATER SOLUTION

measurements of the electrical equivalent conductivity of potassium salts of poly(maleic acid-co-1-olefins), pa-nk2 with n = 12, 18 has been carried out in methanol-water mixtures in the whole range of composition. the relative interaction parameter f*, was determined as a function of the mole fraction of methanol. the values of f* do not follow the same tendency of the limiting equivalent conductivity. this unusual behavior was rationalized in terms of a methanol-induced conformational transition that takes the polymer chain from a compact to an expanded structure. as a consequence of this transition the average charge distance in the polyion increases with increasing mole fraction of methanol. this brings about a decrease of the linear charge density parameter, and therefore an increase of the fraction of polymer charges dissociated from their counterions. the existence of the conformational transition of the pa-nk2 copolymers was confirmed through fluorescence probing experiments