Preparation and characterization of a novel star ABC triblock copolymer of styrene, ethylene oxide, and methacrylic acid

The preparation of a star triblock copolymer based on polystyrene, poly(ethylene oxide), and poly(methacrylic acid) blocks (S-St-EO-MAA) is described. The polymer structure was achieved by the following route: the polystyrene macroanion (PSm) was formed first by a butyllithium-initiated polymerization of styrene and capping with Michler's ketone; the resulting N,N,N′,N′-tetramethyl-4,4′-diaminodiphenylmethanol (TDDM)-terminated polystyrene was further reacted with metal potassium. The oxo-anion initiated the ring-opening polymerization of ethylene oxide, and the desired ABC triblock copolymer was obtained by precipitation polymerization of methacrylic acid (MAA) initiated with a charge transfer complex (CTC) under UV irradiation using benzene as a solvent. The complex is composed of PS-b-PEO with a TDDM end group (PS-b-PEOtm) and benzophenone (BP).