Estimation of bound quaternary ammoniumion to a rod-like polyion with a large alkyl residue

The amount of quaternary ammonium ion (Bu4N+), which is believed not to be bound to general carboxylpolyelectrolytes, bound to poly(iso BVE-co-MA) was estimated by conductivity measurements. In the region of the density of polyion charge in which the polyions are thought to take a free drain'ng conformation, it has been confirmed that the activity coefficient of Bu4N+ ions is less than 0.5 in the presence of a small amount of Bu4NCl, showing that the force between the counterions and the polyion is probably due to the hydrophobic interaction. Moreover, from the electrophoretic mobility Up of the polyion observed from the data of conductivity, it has been ascertained that Up of this polyion is two times larger than PAA, and the behavior of the quantity e/xiP with changing degree of ionization corresponds to that of the viscosity.