Self-Assembly of Poly(Janus particle)s into Unimolecular and Oligomeric Spherical Micelles

Using shape-persistent Janus particles to construct poly­(Janus particle)­s and studying their self-assembly behaviors are of great interest, but remain largely unexplored. In this work, we reported a type of amphiphiles constructed by the ring-opening metathesis polymerization of nonspherical molecular Janus particles (APOSS-BPOSS), called poly­(Janus particle)­s (poly­(APOSS-BPOSS)n, n = 12, 17, 22, and 35, and Mn = 35–100 kg/mol). Unlike traditional bottlebrush polymers consisting of flexible side chains, these poly­(Janus particles) consist of rigid hydrophilic and hydrophobic polyhedral oligomeric silsesquioxane (POSS) cages as side chains. Interestingly, instead of maintaining an expected extended chain conformation, they could also collapse and then self-assemble to form unconventional unimolecular or oligomeric spherical micelles in solutions with a feature size smaller than 7 nm. More importantly, unlike traditional amphiphilic polymer brushes that could form unimolecular micelles at a relatively high degree of polymerization by self-assembly, these poly­(Janus particles)­s could accomplish self-assembly at a quite low degree of polymerization because of their unique chemical structure and molecular topology. The formation of unimolecular and oligomeric micelles was also further confirmed by dissipative particle dynamics simulations. This study of introducing the POSS-based poly­(Janus particle)­s as a class of shape amphiphiles will provide a model system for generating unimolecular and oligomeric micellar nanostructures through solution self-assembly

Sequence-Isomerism-Controlled Macromolecular Self-Assembly in Dendritic Rod-Like Molecules

Although in Nature sequence control is widely adopted to tune the structure and functions of biomacromolecules, it remains challenging and largely unexplored in synthetic macromolecular systems due to the difficulties in a precision synthesis, which impedes the understanding of the structure–property relationship in macromolecular sequence isomerism. Herein, we report the sequence-controlled macromolecular self-assembly enabled by a pair of rationally designed isomeric dendritic rod-like molecules. With an identical chemical formula and molecular topology, the molecular solid angle of the dendron isomers was determined by the sequence of the rod building blocks tethered with side chains of different lengths. As a result, entirely different supramolecular motifs of discs and spheres were generated, which were further packed into a hexagonally packed cylinder phase and a dodecagonal quasicrystalline sphere phase, respectively. Given the efficient synthesis and modular structural variations, it is believed that the sequence-isomerism-controlled self-assembly in dendritic rod-like molecules might provide a unique avenue toward rich nanostructures in synthetic macromolecules

Rational Route Toward the Frank–Kasper Z Phase: Effect of Precise Geometrical Tuning on the Supramolecular Assembly of Giant Shape Amphiphiles

Theoretically, 27 types of Frank–Kasper (FK) phases could be constructed with three cornerstones, the FK A15, C15, and Z phases. They are all spherical packing phases composed of spherical motifs. In single-component soft matter, the experimental observation(s) of the A15 phase is common while C15 and Z phases are rare. Recently, a serendipitous observation of an FK Z phase with significant volume asymmetry of the constructing spherical motifs from a giant shape amphiphile assembly has been reported. In single-component soft matter, it is anticipated that the significant volume asymmetry of spherical motifs consisting of μ and μ ± 1 molecules could be readily reached when the μ is small. Herein, we present a design strategy to precisely control the number of molecules inside a spherical motif by geometrical tuning of the molecular building blocks, thus leading to the formation of the FK Z phase in a rational manner

Continuous Curvature Change into Controllable and Responsive Onion-like Vesicles by Rigid Sphere–Rod Amphiphiles

We observe the formation of highly controllable and responsive onion-like vesicles by using rigid sphere–rod amphiphilic hybrid macromolecules, composed of charged, hydrophilic Keggin-type clusters (spheres) and hydrophobic rod-like oligofluorenes (OFs). Unlike the commonly used approach, which mainly relies on chain bending of flexible molecules to satisfy different curvatures in onion-like vesicles, the rigid hybrids form flexible interdigitations by tuning the angles between OFs, leading to the formation of bilayers with different sizes. The self-assembled vesicles possess complete onion-like structures from most inner to outer layers, and their size (layer number) can be accurately manipulated by different solution conditions including solvent polarity, ionic strength, temperature, and hybrid concentration, with fixed interbilayer distance under all conditions. Moreover, the vesicle size (layer number) shows excellent reversibility to the change of temperature. The charged feature of spheres, rod length, and overall hybrid architecture shows significant effects on the formation of such onion-like vesicles

Topologically Directed Assemblies of Semiconducting Sphere–Rod Conjugates

Spontaneous organizations of designed elements with explicit shape and symmetry are essential for developing useful structures and materials. We report the topologically directed assemblies of four categories (a total of 24) of sphere–rod conjugates, composed of a sphere-like fullerene (C₆₀) derivative and a rod-like oligofluorene(s) (OF), both of which are promising organic semiconductor materials. Although the packing of either spheres or rods has been well-studied, conjugates having both shapes substantially enrich resultant assembled structures. Mandated by their shapes and topologies, directed assemblies of these conjugates result not only in diverse unconventional semiconducting supramolecular lattices with controlled domain sizes but also in tunable charge transport properties of the resulting structures. These results demonstrate the importance of persistent molecular topology on hierarchically assembled structures and their final properties