The anisotropic orientational and positional ordering of liquid crystals (LCs) confers useful optical, magnetic, and electronic properties. Within the range of structures achievable, a specialized class of low symmetry, highly crystalline, ‘B-phases’ can arise from mesogens with a bent geometry. Specialized, highly ordered LC structures including helical, heliconical, and chiral structures, have been discovered in bent-core systems, inspiring materials applications in medicine, bio-sensors, and catalysis. Studies of these LCs systems will further knowledge of the fundamental interactions driving the formation of these packing schemes and improve their viability for use in fields ranging from biomaterials to electronics. This study examines the self-assembly of two achiral, asymmetrical mesogenic heterodimers, which, because of their flexible core, can adopt a bent geometry. The dimers contain two constituent monomer units—a phenyl benzoate core both with (M) and without (P) a methyl-substituent on an aromatic ring. These two heterodimers (MP and PM) both exhibit nanocylinders ~150 nm in diameter that assemble into hierarchical structures with emergent chirality. The crystalline forms investigated via optical, thermal, and X-ray characterization differed between the two dimers and with crystallization conditions, indicating the role of the precise placement of the methyl group on the packing mechanism. Equimolar blends of the MP and PM dimers did not form nanocylinders, instead forming a microstructure of twisted lamellae. Free surface crystallization studies illuminated the competing factors that drive the formation of the nanocylinder self-assembly and their chiral superstructures. Additionally, the effect of isothermal crystallization temperature and chemical surface treatments on crystallization kinetics was probed. Discerning the origin of structures present in this heterodimer system and further studies improving control over their confirmation and growth will strengthen current research efforts on the fundamental competing interactions driving chirality and symmetry breaking in LC hierarchical self-assemblies.
