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Droplet-confined assembly is a powerful tool to fabricate functional nanostructures of block copolymers (BCPs), where the interfacial interaction plays a crucial role. Here, we report an unconventional strategy of using interfacial phase separation to control this assembly. The key lies in the use of an elaborately designed binary surfactant system to tune the interfacial configuration of droplets and realize an asymmetrically directed assembly of BCPs inside droplets, which finally creates unprecedented Janus onion particles with solid surfactant-like properties, e.g., as stabilizers for Pickering emulsions. The formation of Janus onions is due to the strong longitudinal selective interaction and the strong lateral phase separation at the droplet interfaces, provided by our surfactant system. This concept of interfacial phase separation directed assembly not only enriches the routes to controllable assembly of BCPs, but also offers an innovative paradigm to construct distinct regions on droplet surfaces, illuminating potential functions such as smart encapsulation and delivery. Image 1 1. Interfacial phase separation of emulsion droplets was firstly used to direct the droplet-confined assembly of block copolymers. 2. Unprecedented Janus onion-like particles of block copolymers were fabricated. 3. The Janus onions could act as particulate surfactants to stabilize Pickering emulsion. [ABSTRACT FROM AUTHOR]

A facile and electrostatically driven approach has been developed to prepare bicontinuous polymer nanocomposites that is based on the polyoxometalate (POM) macroion induced phase transition of PS- b-P2VP from an initial lamellar phase to a stable bicontinuous phase. The multi-charged POMs can electrostatically cross-link P2VP blocks and give rise to bicontinuous phases in which the POM hybrid conductive domains occupy a large volume fraction of more than 50 %. Furthermore, the POMs can give rise to high proton conductivity and serve as nanoenhancers, endowing the bicontinuous nanocomposites with a conductivity of 0.1 mS cm−1 and a Young's modulus of 7.4 GPa at room temperature; these values are greater than those of pristine PS- b-P2VP by two orders of magnitude and a factor of 1.8, respectively. This approach can provide a new concept based on electrostatic control to design functional bicontinuous polymer materials. [ABSTRACT FROM AUTHOR]

3D confined assembly in emulsion droplets is an effective way to prepare block copolymer particles with tunable nanostructures. In this process, the multi-component interaction at the droplet interface plays a crucial role, which is mainly dominated by surfactants. Here, we report the utilization of a polymer surfactant, ammonium-terminated polystyrene chains (N–PS n), to control the 3D confined assembly of poly(styrene- block -2-vinylpyridine) (PS- b -P2VP). N–PS n shows a different interfacial tuning ability from small molecular surfactants, which can not only stabilize the emulsion droplets but also increase the volume fraction of PS components through fusing its PS chains with PS- b -P2VP. Consequently, unusual nanostructured PS- b -P2VP particles were obtained based on a binary surfactant system of N–PS n and poly(vinyl alcohol), e.g. , the rarely reported toroid-stacked ellipsoidal particles. The morphological formation mechanism was systemically studied by regulating the molecular weight of N–PS n. These results provide a new surfactant platform to tune the confined assembly of block copolymers. Image 1 • A unique 3D confined assembly of block copolymers was realized by using polymer surfactants. • Unusual ellipsoidal polymer particles with axially stacked toroidal domains were obtained. • Cationic polymer surfactants with adjustable interfacial controlling ability were synthesized. [ABSTRACT FROM AUTHOR]