N-methylene phosphonic chitosan. Effect of preparation methods on its properties

N-methylene phosphonic chitosan is prepared from chitosan with different acetylation degrees and sources using three reaction times. The degree of substitution is not dependent on chitosanʹs source and degree of deacetylation but it depends on reaction time. Data are confirmed by 1H NMR and FT-IR. A significant decrease of viscosity and molecular weight is observed due to derivatization. It is demonstrated that N-methylene phosphonate chitosan is a powerful chelating agent of transition metal and calcium ions.