Recent developments in cellulose grafting chemistry utilizing barton esterintermediates and nitroxide mediation

Esters or carbonates of N-hydroxypyridine-2-thione (Barton esters) were app ended to either carboxymethyl or hydroxypropyl cellulose. Irradiation of th e cellulose bound Barton esters in monomer initiated free radical graft cop olymerization with minimal concomitant homopolymerization. Grafting of styr ene to carboxymethyl cellulose was accompanied by backbone cleavage. The hy droxypropyl spacer group minimized backbone degradation; styrene, acylamide and N-isopropyl acrylamide could be grafted to hydroxypropyl cellulose in tetrahydrofuran solution. Treatment of Barton carbonate modified hydroxypro pyl cellulose with styrene in the presence of TEMPO afforded corresponding TEMPO adducts, which can be used to promote the controlled radical graft po lymerization of styrene. Grafts were analyzed independently after hydrolysi s of the cellulose backbone.