title: Temperature-induced structure switch in thermo-responsive micellar interpolyelectrolyte complexes: toward core-shell-corona and worm-like morphologies.
abstract: The spontaneous formation and thermo-responsiveness of a colloidally-stable interpolyelectrolyte complex (IPEC) based on a linear temperature-sensitive diblock copolymer poly(vinyl sulfonate)31-b-poly(N-isopropyl acrylamide)27 (PVS31-b-PNIPAM27) and a star-shaped quaternized miktoarm polymer poly(ethylene oxide)114-(poly(2-(dimethylamino)ethyl methacrylate)17)4 (PEO114-(qPDMAEMA17)4) was investigated in aqueous media at 0.3 M NaCl by means of dynamic light scattering (DLS), small angle X-ray scattering (SAXS), and cryogenic transmission electron microscopy (cryo-TEM). The micellar macromolecular co-assemblies show a temperature-dependent size and morphology, which result from the lower critical solution temperature (LCST) behavior of the PNIPAM-blocks. Hence, the micellar co-assemblies grow upon heating. At 60 °C, spherical core-shell-corona co-assemblies are proposed with a hydrophobic PNIPAM core, a water-insoluble IPEC shell, and a hydrophilic PEO corona. These constructs develop into a rod-like structure upon extended equilibration. In turn, PEO-arms and PNIPAM-blocks within a hydrophilic mixed two-component corona surround the water-insoluble IPEC domain at 20 °C, thereby forming spherical core-corona co-assemblies. Reversibility of the structural changes is suggested by the scattering data. This contribution addresses the use of a combination of oppositely charged thermo-responsive and bis-hydrophilic star-shaped polymeric components toward IPECs of diverse morphological types.
authors.affiliation: Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany. plamper@pc.rwth-aachen.de.
authors.forename: Claudia
authors.initials: C
authors.lastname: Dähling
authors.forename: Gudrun
authors.initials: G
authors.lastname: Lotze
authors.forename: Markus
authors.initials: M
authors.lastname: Drechsler
authors.forename: Hideharu
authors.initials: H
authors.lastname: Mori
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Pergushov
authors.forename: Felix A
authors.initials: FA
authors.lastname: Plamper