Water-Soluble Complexes Formed by Poly(2-vinylpyridinium)-<i>b</i><i>lock</i>-poly(ethylene oxide) and Poly(sodium methacrylate)-<i>b</i><i>lock</i>-poly(ethylene oxide) Copolymers

Abstract

Formation of interpolyelectrolyte complexes (IPEC) by mixing protonated poly(2-vinylpyridine)-block-poly(ethylene oxide) (P2VP-b-PEO) with neutralized poly(methacrylic acid)-block-poly(ethylene oxide) (PMAA-b-PEO) has been investigated in water. It was observed that (i) IPEC are formed in a limited pH range, which is controlled by the degree of ionization of the PMAA and P2VP blocks; (ii) IPEC self-assemble to form the core of monodisperse spherical micelles surrounded by a corona of PEO blocks; (iii) IPEC are salt-sensitive, falling apart above a critical salt concentration; (iv) IPEC are not observed at high pH, but micelles are formed by the P2VP-b-PEO copolymers, which contain an uncharged P2VP core surrounded by a PEO corona; (v) IPEC are not observed at low pH, but the PMAA-b-PEO diblocks aggregate into micelles, the core of which is formed by a hydrogen-bonded complex between PMAA and PEO; and (vi) these PMAA-b-PEO micelles, which are temperature-sensitive, show a complete reorganization of the micellar core above a critical temperature.