Synthesis and aqueous solution behavior of phosphonate-functionalized chitosans

A series of novel phosphonate-functionalized pH-responsive chitosans were directly synthesized via Michael addition of chitosan with mono-(2-acryloyloxyethyl) phosphonate. The conformational and phase transitions of these phosphonate-functionalized chitosans were investigated by turbidity and UV–vis spectroscopy studies. The results indicated that the inter- or intra-chain electrostatic interactions of the phosphonate-functionalized chitosans could be controlled via adjusting the solution pH, leading to the reversible conformational and phase transitions of these chitosans. These phosphonate-functionalized chitosans exhibited typical anti-polyelectrolyte effect and polyelectrolyte effect.