Synthesis of graft copolymer derivatives of brominated poly(isobutylene-co-isoprene)

Strategies for preparing graft copolymers from brominated poly(isobutylene-co-isoprene) (BIIR) are demonstrated. Selective dehydrohalogenation of the allylic bromide functionality within BIIR to give an exo-conjugated diene is described, along with subsequent cycloadditions of maleic anhydride (MAn) and its mono-ester and di-ester derivatives. Alcoholysis of the bicyclic anhydride product of BIIR dehydrobromination/MAn cycloaddition is used to produce an IIR-g-PE copolymer in low yield. An alternate approach involving bromide displacement from BIIR by the salts of maleate half-esters is shown to be an efficient means of generating isobutylene-rich copolymers containing polyethylene, polyethylene oxide and polycaprolactone grafts.