Effects of polyelectrolyte complexation on the UCST of zwitterionic polymer

A zwitterionic polymer-poly-3-dimethyl(methacryloyloxyethyl)ammonium propan e sulfonate (PDMAPS)-was synthesized and its complexation behaviors with po lyanion: poly-2-acrylamido-2-methyl propane sulfonic acid (PAMPS); and poly cation: poly-3-acryloylamino propyl trimethyl ammonium chloride (PDMAPAA-Q) ; or: x,y-ionene bromides (x = 3,6; y = 3,4) have been studied. One of the characteristic features of these complexes is that they are soluble, in spi te of the abolishment of positive or negative charge of PDMAPS after the co mplexation and is able to exhibit UCST depending on the concentration and t he mixing molar ratio. It was found that PDMAPS-PAMPS complex dramatically increases the viscosity to give a network structure through electrostatic i nteraction extensively decreasing the UCST, while the PDMAPS-polycation com plex first decreases, but then increases the UCST without forming the netwo rk. The mechanism of different behaviors of these complexes has been discus sed. (C) 1999 Elsevier Science Ltd. All rights reserved.