Synthesis and characterization of poly(acrylamidoglycolic acid) grafted onto chitosan and its polyelectrolyte complexes with hydroxyapatite

Graft copolymerization of acrylamidoglycolic acid (AGA) onto chitosan (CS) was carried out via a free radical initiation mechanism using a redox initiation system. Grafting ratio (%), efficiency, and conversion (%) were all found to depend on the content of potassium persulfate and AGA as well as on reaction temperature and time. Evidence of grafting was obtained by FTIR, 13C NMR spectra, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. Hydroxyapatite (HA) polyelectrolyte complexes (PEC) were prepared by in situ addition of HA to the polymerization medium under optimal reaction conditions. Complexes were prepared using different ratios of HA with respect to CS-g-PAGA graft copolymers. The synthesized PECs were evaluated in swelling studies in phosphate-buffered saline. A mechanism for the free radical grafting and HA complexation were proposed.