Growth Mechanism of Polyelectrolyte Multilayers

Abstract

In this chapter, QCM-D is employed to systematically study the influences of temperature, pH, salt concentration, salt type, chain flexibility, and chain architecture on the growth of polyelectrolyte multilayers. In the case of sodium poly(styrene sulfonate)/poly[2-(dimethylamino)ethyl methacrylate] multilayer, the multilayer growth is dominated by the chain interpenetration which can be modulated by varying temperature, pH, and salt concentration. In the case of sodium poly(styrene sulfonate)/poly(diallyldimethylammonium chloride) multilayer, the multilayer growth is dominated by chain conformation and chain interpenetration at C NaCl \ 1.0 M and C NaCl C 1.0 M, respectively. The specific ion effect on the growth of polyelectrolyte multilayers can be observed in water, methanol, as well as their mixtures, and the ion specificity is determined by the specific interactions between the charged groups and the counterions. When the multilayer is constructed by two semiflexible polyelectrolytes, the multilayer growth is controlled by the delicate balance between the weakening of electrostatic repulsion between the identically charged groups on the same chain and the decrease of electrostatic attraction between the neighboring layers with the increase of salt concentration. The influence of arm number on the chain interpenetration during the multilayer growth is dominated by the steric effect created by the arm chains.