Shapes of Polyelectrolyte Titration Curves. 2. The Deviant Behavior of Labile Polyelectrolytes

Hydroxypropyl guar (HPG), a nonionic water soluble polymer, becomes an anionic polyelectrolyte in the presence of borate or boronate ions which bind to HPG. However, the charge groups on the HPG−borate are labile which complicates the interpretation of polyelectrolyte titration behavior. Specifically, polyelectrolyte complex formation between HPG−borate and cationic poly(diallyldimethyl ammonium chloride), PDADMAC, stimulates further borate binding to HPG. We propose that labile polyelectrolytes such as HPG−borate are new class of polylelectrolytes that fall outside conventional “strong” or “weak” polyelectrolyte behavior.