Discrete Diblock Copolymers with Precise Stereoconfiguration

This work develops an iterative growth approach to synthesize discrete oligo lactic acids with exactly defined stereoconfiguration by connecting enantiomeric monomers (i.e., L- and D-lactic acid) following a predesigned sequence. A library of diblock copolymers with uniform chain length was modularly prepared by conjugating the stereoisomeric blocks with a chemically incompatible chain. The precise chemical structure eliminates all molecular uncertainties associated with statistical distribution and decouples the intertwined variables. A rich collection of ordered structures, including unconventional Frank–Kasper A15 and σ phases, was captured. The stereoconfiguration exerts pronounced impacts on chain conformation, leading to appreciable variations of lattice dimension and phase stability. This study quantitatively assessed the critical contribution of stereoconfiguration on packing behaviors, calling for particular attention to this essential molecular parameter as an effective handle for rational structural engineering

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

Superlattice Engineering with Chemically Precise Molecular Building Blocks

Correlating nanoscale building blocks with mesoscale superlattices, mimicking metal alloys, a rational engineering strategy becomes critical to generate designed periodicity with emergent properties. For molecule-based superlattices, nevertheless, nonrigid molecular features and multistep self-assembly make the molecule-to-superlattice correlation less straightforward. In addition, single component systems possess intrinsically limited volume asymmetry of self-assembled spherical motifs (also known as “mesoatoms”), further hampering novel superlattices’ emergence. In the current work, we demonstrate that properly designed molecular systems could generate a spectrum of unconventional superlattices. Four categories of giant molecules are presented. We systematically explore the lattice-forming principles in unary and binary systems, unveiling how molecular stoichiometry, topology, and size differences impact the mesoatoms and further toward their superlattices. The presence of novel superlattices helps to correlate with Frank–Kasper phases previously discovered in soft matter. We envision the present work offers new insights about how complex superlattices could be rationally fabricated by scalable-preparation and easy-to-process materials

Ordered Mesoporous Silica Pyrolyzed from Single-Source Self-Assembled Organic–Inorganic Giant Surfactants

We report the preparation of hexagonal mesoporous silica from single-source giant surfactants constructed via dihydroxyl-functionlized polyhedral oligomeric silsesquioxane (DPOSS) heads and a polystyrene (PS) tail. After thermal annealing, the obtained well-ordered hexagonal hybrid was pyrolyzed to afford well-ordered mesoporous silica. A high porosity (e.g., 581 m2/g) and a uniform and narrow pore size distribution (e.g., 3.3 nm) were achieved. Mesoporous silica in diverse shapes and morphologies were achieved by processing the precursor. When the PS tail length was increased, the pore size expanded accordingly. Moreover, such pyrolyzed, ordered mesoporous silica can help to increase both efficiency and stability of nanocatalysts

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