A series of novel acidic and zwitterionic water-soluble diblock copolymers has been synthesized directly (i.e. without protecting group chemistry) via the TEMPO-mediated living free-radical polymerization of various hydrophilic styrenic monomers. In all syntheses TEMPOcapped poly(sodium 4-styrenesulfonate) was utilized as a well-defined macro-initiator. Chain extension of this macro-initiator with 2vinylpyridine proved very inefficient. Using 4-vinylbenzyltrimethylammonium chloride as comonomer led to an insoluble zwitterionic complex, whereas water-soluble zwitterionic block copolymers were obtained with 4-(dimethylamino)methylstyrene. Micellar solutions were obtained with the less hydrophilic 4-vinylbenzyl alcohol comonomer. A series of strong acid–weak acid block copolymers with varying sodium 4-styrene-sulfonate contents (20–80 mol%) were prepared via chain extension of the macro-initiator using sodium 4-styrenecarboxylate. These acidic block copolymers undergo reversible pH-induced aggregation in aqueous solution and 13C n.m.r. spectroscopy studies suggest that the carboxylic acid block forms the hydrophobic micellar core. Dynamic light scattering studies indicate intensity-average micelle diameters of 20–60 nm.
Посилання на статтю:
Direct synthesis of novel acidic and zwitterionic block copolymers via TEMPO-mediated living free-radical polymerization / L.I. Gabaston, S.A. Furlong, R.A. Jackson, S.P. Armes // Polymer. – 1999. – N 40. – P. 4505–4514.