The structure of charged spherical block copolymer micelles in aqueous solution was investigated with static and dynamic light scattering, small-angle neutron scattering, and cryo-electron microscopy as a function of added salt. At low added salt concentration the polyelectrolyte shell has typical features of an osmotic brush. If the added salt concentration exceeds the intrinsic ionic strength of the polyelectrolyte shell, the micellar aggregation number increases due to screening of the repulsive interaction between polyelectrolyte chains (salted brush). The relation between shell ionic strength and added salt concentration follows a simple Donnan equilibrium. The combination of methods reveals that the polyelectrolyte shell is phase-separated into a dense interior and a dilute outer domain.

The association behavior of polyelectrolyte block copolymers in aqueous solution as a function of polymer and salt concentration is investigated for poly(ethylethylene-b-styrenesulfonic acid) (PEE-PSSH). This copolymer combines a soft hydrophobic block with a highly charged polyelectrolyte block that allows direct dissolution in aqueous solutions to investigate micellization under equilibrium conditions. Increasing polymer and salt concentration leads to the fusion of polyelectrolyte micelles into vesicles and fractal toroid-micronetworks. Association structures were characterized by static light scattering (SLS), small-angle neutron scattering (SANS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). At high salt concentrations the solution phase separates into a dilute micellar phase and a concentrated gel phase.

Abstract. -In this paper we present an experimentally determined phase diagram of binary blends of the diblock copolymers poly(styrene)-poly(isoprene) and poly(isoprene)-poly(ethylene oxide). At high temperatures, the blends form an isotropic mixture. Upon lowering the temperature, the blend macro-phase separates before micro-phase separation occurs. The observed phase diagram is compared to theoretical predictions based on experimental parameters. In the low-temperature phase the crystallisation of the poly(ethylene oxide) block influences the spacing of the ordered phase.Binary blends of polymers are immiscible at low temperatures in the case of upper critical solution temperature behaviour, leading to macro-phase separation below a binodal line. In contrast, phase separation in single-component block copolymers leads to micro-phase separation (below an order-disorder transition) because macro-phase separation is prevented by the connectivity of the polymer chains. In blends of a block copolymer with a homopolymer or in blends of block copolymers an interesting interplay occurs between micro-and macrophase separation. Previous experimental and theoretical work on these systems has been reviewed [1]. Here, we probe phase-separated structures in binary blends of block copolymers with one common B-block, AB/BC. In contrast to binary blends of AB block copolymers, the phase behaviour of this AB/BC system is predicted to be much richer, because there are three independent Flory-Huggins interaction parameters.Recent theoretical work highlights the possibility of intriguing critical phenomena, such as Lifshitz points, resulting from the competition between micro-and macro-phase separation in AB/BC block copolymer blends [2]. To date, there has been little experimental work on such systems. Kimishima et al. [3] have investigated the phase behaviour of 50:50 blends of a poly(styrene)-poly(ethylene-co-propylene) diblock copolymer with one of a series c EDP Sciences