Variations of the Williamson ether synthesis were employed to prepare a range of new derivatives of brominated. poly(isobutylene-co-isoprene) (BIIR). Unambiguous characterization of the polymeric products was accomplished by spectroscopic comparisons to low-molecular-weight analogues derived from brominated 2,2,4,8,8-pentamethyl-4-nonene, which served as a model for the reactive functionality found within BIIR. The substitution of bromide from BIIR occurred at moderate temperatures with stoichiometric amounts of quaternary ammonium phenoxide to yield O-alkylation products in high yields. Simple mixtures of BIIR, KOH, and aliphatic alcohols generated the desired allylic ethers when heated above 110 C in the absence of quaternary ammonium salts. Knowledge gained from these small-molecule alkylations was used to prepare graft copolymers from BIIR and poly(ethylene oxide) through the exploitation of the apparent ability of polyethers to activate potassium alkoxides in nucleophilic substitutions. (c) 2005 Wiley Periodicals, Inc.