ИСТИНА

The generation of defined micellar morphologies via a controlled self-/co-assembly in multicomponent polymer systems is currently being intensively investigated. A straightforward way to achieve formation of micellar structures is co-assembly of oppositely charged bis-hydrophilic (ionic/non-ionic) copolymers. If the non-ionic block is stimuli-sensitive, it might enable sequential switching of the micellar structures. An interpolyelectrolyte complex (IPEC) was formed in aqueous NaCl solution between a linear diblock copolymer poly(vinyl sulfonate)31-b-poly(N-isopropylacrylamide)27 (PVS31-b-PNIPAM27) and a star-shaped heteroarm quaternized copolymer poly(ethylene oxide)114-(poly(2-(dimethylamino)ethyl methacrylate)17)4 (PEO114-(qPDMAEMA17)4). Dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) studies were performed to elucidate the size, shape and structure of the co-assemblies as a function of temperature. The scattering data (Figure 1, B-E) prove the spontaneous formation of colloidally-stable micellar IPECs and reveal the temperature dependence of size and aggregation number resulting from the lower critical solution temperature (LCST, ≈ 32 °C) behavior of the PNIPAM blocks. SAXS experiments further imply structural changes of the micellar structure showing reversibility upon crossing the LCST. At T < LCST the formation of complexes with core-corona (IPEC core)-(PEO/PNIPAM corona) structure is expected, whereas at T > LCST the formation of spherical core-shell-corona (PNIPAM core)-(IPEC shell)-(PEO corona) co-assemblies is proposed. SAXS data obtained from an IPEC solution equilibrated at 60 °C suggest the formation of worm-like micellar structures coexisting with spherical micelles.