IONIC POLYMERS .3. SORPTION OF FE(III) IONS ON NEW CROSS-LINKED IONICPOLYMERS BASED ON 4-VINYLPYRIDINE - DIVINYLBENZENE COPOLYMERS

Copolymers of 4-vinylpyridine : divinylbenzene with various degrees of crosslinking have been obtained as precursors for ionic polymers. To this end, addition reactions of the 4-vinylpyridine : 8% divinylbenzen e copolymer to electrophylic ethylenic compounds, such as acrylamide, acrylonitrile, and methyl vinyl ketone in the presence of HCl have bee n performed; the resulting ionic polymers contain, besides ammonium qu aternary groups, other functional groups such as amide, nitrile, and k etone. The quantitative iron retention from aqueous Fe-2(SO4)(3) solut ions was determined photocolorimetrically for both 4-vinylpyridine : d ivinylbenzene copolymers and the synthesized ionic polymers. IR and Mo ssbauer spectroscopy were used to determine the state of the Fe(III) i ons in the tridimensional networks. As expected, in 4-vinylpyridine : divinylbenzene copolymers, Fe(III) ions are retained by nitrogen atoms -Fe(III) complexes. The electronic state of metal ions hardly depends on the crosslinking degree. In the ionic polymers, the Fe(III) ions ar e retained through ionic exchange as the R(4)N(+)[Fe-3(SO4)(2)(OH)(6)] (-) complex anion. The functional amide, nitrile, and ketone groups, a lthough containing atoms able to form donor-acceptor bonds, do not tak e part in the complexation. (C) 1996 John Wiley & Sons, Inc.