Polyphosphate-Chitosan Polyelectrolyte Complexation

The literature on complexation between chitosan and sodium polyphosphates is limited to very short polyphosphates with degrees of polymerization of 2 to 6. Here, for the first time, polyelectrolyte complexation between chitosan and moderately long (Dp = 22) polyphosphates was studied. Using turbidity measurements, optical microscopy, and visual observations the phase diagram of the system was determined and compared to a traditionally deployed tripolyphosphate system. Such diagrams are rare but could be important to anticipate the products of a reaction of specific polyelectrolyte pairs. It was shown that this chitosan-polyphosphate system is not capable of forming coacervates and is therefore more appropriate for developing solid rather than liquid biomaterial precursors.