Prismatic Block Copolymer Hexosomes

Abstract

Cubosomes and hexosomes are recent solution morphologies with an ordered porous structure and are observed for lipids and amphiphilic block copolymers (BCPs) with high hydrophobic fractions. Whereas lipid hexosomes typically exhibit a prismatic shape, BCP hexosomes have so far only been observed as closed microspheres where inner channels are not connected to the surrounding medium. Here, we describe the formation of flat, prismatic BCP hexosomes with pronounced faceting and a highly ordered lattice of hexagonally packed channels. We assemble polystyrene-block-poly­(4-vinylpyridine) (PS-b-P4VP or SV) into the hexosome framework using polystyrene-block-poly­(4-vinylpyridine)-block-poly­(tert-butyl methacrylate) (PS-b-P4VP-b-PT or SVT) as a macromolecular surfactant in low-χ solvents. During solvent exchange, SV-rich domains form through liquid–liquid phase separation, followed by solidification and confined assembly within these domains. Since the final solvent (acetone) has a very low χ parameter toward PS and P4VP (equaling low interfacial tension), solidification of the hexosome occurs under confinement conditions that we term “supersoft”. The low interfacial tension allows the stabilization of the hexagonal-prismatic shape, which originates from the hexagonal lattice of channels. Increasing the interfacial tension with polar cosolvents at some point dominates the particle shape, resulting in deformation of prismatic BCP hexosomes into spinning-top structures. The use of low-χ solvents for confined assembly of BCPs may allow the formation of unusual particle shapes simply by tuning the polymer–solvent interaction.

Photocleavable Polymer Cubosomes: Synthesis, Self-Assembly, and Photorelease

“…Increasing the hydrophobic block to f PNBMA = 92.7 wt %, PEG 45 - b -PNBMA 90 self-assembled into PCs with an average diameter of 3.6 μm (Figure e–h and Figure S7). Remarkably, the PC surface displayed the formation of well-developed terraces and facets (Figure g), which are typically only observed for crystalline colloidal clusters. , As far as we are aware, such a pronounced external faceting has not been reported for PCs before that are usually polished into spheres by interfacial tension with only minor indication of being polyhedra. , We recently reported on PHs in organic solvents that were able to adopt a hexagonal prismatic shape with monocrystalline p 6 mm lattice, which we attributed to the very low interfacial tension toward the polymer blocks . Since we are in water with much higher interfacial tension, it is more likely that the PNBMA block has a strong packing tendency, surmounting the curvature of the particle interface.…”

Impact of channel nanostructures of porous carbon particles on their catalytic performance

“…19–27 This method allows for the synthesis of particles with diverse particle shapes and internal structures, such as spherical particles with lamellar and coiled cylinder structures, football-like particles, and lens-shaped particles. 21,25,28,29 Particularly, continuous channel structures within the particles can be achieved by controlling the BCP structures and selectively etching one of the BCP domains. 30–34 Among the various methods for controlling the orientation of the BCP and channel nanostructure, modulation of the solvent-evaporation rate is an effective technique to achieve continuous channels exposed to the particle surface.…”