A novel bifunctional monomer, namely, 4-(vinylphenyl)-1-butene (VSt), was prepared by the coupling reaction between vinylbenzyl chloride and allylmagnesium chloride with a high yield (93%) and monomer purity. This monomer contains both a styrene type and a l-butene type C=C double bond. The former double bond can be selectively polymerized by anionic polymerization to generate a polymer with a polystyrene [poly(St)] backbone and functional butenyl side chains. The effects of the initiator, temperature, and solvent were investigated, and the optimum conditions for the selective living anionic polymerization of this monomer were determined. Using n-BuLi as initiator, in a mixture of toluene and tetrahydrofuran (5:1-2:1), at -40 degrees C, VSt could undergo anionic polymerization in a living manner without cross-linking and any other side reactions. The polymer thus obtained possesses a controlled molecular weight and a very narrow molecular weight distribution (M-w/M-n = 1.03-1.05). The quantitative presence of the unreacted 1-butene type C=C double bonds was verified by H-1 NMR and FT-IR. The block copolymerization of VSt and St could also proceed smoothly in the polymerization sequence VSt followed by St, or vice versa, to generate a well-defined block copolymer with a controlled molecular weight and composition and a very narrow molecular weight distribution (M-w/M-n = 1.03-1.07). The C=C double bonds of the side chains of poly(VSt) were further reacted first with 9-borabicyclo [3.3.1]nonane (9-BBN), followed by the addition of sodium hydroxide and hydrogen peroxide. This procedure generated a uniform size hydrophilic functional polymer, poly(4-hydroxybutylstyrene), without destroying the main-chain structure of the polymer. This hydroxylation method was also applied to the block copolymer of VSt and St, and a well-defined amphiphilic block copolymer, containing both the hydrophilic poly(4-hydroxybutylstyrene) and the hydrophobic poly(St) segments, was obtained.