A new bifunctional monomer, trans,trans- 1-methacryloyloxy-2,4-hexadiene (MAHE), was prepared through the reaction between the sodium salt of 2,4-hexadien-1-ol and methacryloyl chloride. Using 1,1-diphenylhexyllithium (DPHL) as initiator, in THF, in the presence of LiCl ([LiCl]/[DPHL](0) = 3), at -70 degreesC, the anionic polymerization of MAHE proceeded quantitatively, generating monodisperse polymers (M-w/M-n = 1.04-1.05) with well-controlled molecular weights. Under similar conditions, well-defined block copolymers with controlled molecular weights and compositions as well as very narrow molecular weight distributions (M-w/M-n, = 1.04-1.06) were prepared by the anionic block copolymerization of MAHE and MMA, regardless of the polymerization sequence (MAHE followed by MMA or vice versa). Similarly, the copolymers resulting from the random copolymerization of these two monomers possessed monodispersity (M-w/M-n, = 1.04-1.05), regardless of the feed amount ratio. Further, block copolymers of St and MAHE with various compositions were obtained by the anionic block copolymerization of MAHE to a 1,1-diphenylethylene-capped anionic living poly(St). In both the homopolymerization of MAHE and its copolymerization with MMA or St, its 2,4-hexadienyl side group remained unreacted. This side group was further reacted with bromine or osmium tetroxide. Using an excess amount of bromine, at room temperature, the bromination efficiency reached 95%, generating a new functional polymer, poly(2,3,4,5-tetrabromohexyl methacrylate). The osmylation was carried out by reacting the (co)polymer with an excess of N-methylmorpholine N-oxide, in the presence of a small amount of osmium tetroxide as catalyst, at room temperature. This osmylation reaction changed poly(MAHE) to a new functional polymer, poly-(2,3,4,5-tetrahydroxyhexyl methacrylate), with an extremely high water solubility. Well-defined amphiphilic block copolymers were also obtained via the osmylation after block copolymerizations.