Tetragonal phase of cylinders self-assembled from binary blends of AB diblock and (A'B)n star copolymers

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.

Formation of homochiral helical nanostructures in diblock copolymers under the confinement of nanopores

The control of the homochirality of helical structures formed in achiral systems is of great interest as it is helpful for understanding the origin of homochirality in life.

Emergence and Stability of a Hybrid Lamella-Sphere Structure from Linear ABAB Tetrablock Copolymers

The self-assembly of linear A₁B₁A₂B₂ tetrablock copolymers is studied using the self-consistent field theory, aiming to target the formation of stable hybrid structures composed of lamellar and spherical domains of the same component, i.e., the lamella-sphere (LS) phase. Two types of lamellar morphologies, regular (L) and sandwich-like (L'), are observed, and their transition is identified as first-order. The formation of L' is a prior condition for the formation of LS because the disordered short A₂-blocks sandwiched in the B domain in L' aggregate into spheres as χN increases, leading to the formation of LS. The separation of A₂-blocks from A₁-blocks in L' or LS causes extra interfacial energy, which is compensated by the gain of configurational entropy. The tail B₂-block is demonstrated to play a critical role in enlarging the gain of configurational entropy. In a word, the formation of L' is driven by entropy, while the transition from L' to LS is driven by enthalpy.