Block Copolymers of Styrene, Isoprene, and Ethylene Synthesis and Characterization Oxide Prepared by Anionic Polymerization. I

Anionic polymerization has been used as a technique for the synthesis of five-block copolymers of polystyrene (PS), polyisoprene (PI), and poly(ethy1ene oxide) (PEO). Two types of such polymers, PEO-PI-PS-PI-PEO and PEO-PS-PI-PS-PEO with varying PEO block length, have been prepared, using potassium naphthalene as the initiator and tetrahydrofuran as the solvent. The polymers were purified by extraction with ethyl acetate, diethyl ether, and water. After the additiowof each monomer, a sample from the living polymer solution was taken and analyzed by spectroscopy (infrared (IR) and proton magnetic resonance (PMR)), osmometry, and gel-permeation chromatography (GPC) to obtain information about composition, molecular weight, and molecular weight distribution of the intermediate polymers. The five-block copolymers have also been characterized by the same techniques and by elemental analysis.