The Thermodynamic Origins of Chiral Twist in Monolayer Assemblies of Hard Rod-like Colloids

Abstract

The propagation of chirality across scales is a common but poorly understood phenomenon in soft matter. In this work, we use computer simulations to study chiral monolayer assemblies formed by hard rod-like colloidal particles in the presence of non-adsorbing polymer and characterize the thermodynamic driving forces responsible for the twisting. Simulations show that straight (achiral) rods assemble into monolayers with a spontaneous twist that is either left- or right-handed, while helical (chiral) rods lead to assemblies with preferential chiral features that depend on their handedness and curliness. The onset of chirality in these monolayers can be traced back to small clusters formed at the initial stage of the self-assembly. In these microscopic monolayers, entropy drives twisting in ways that differ from the assumptions on which existing continuum theory is built. Depending on the geometry of the constituent rods, the preferred chiral twist can be driven by entropy gain of the polymers, or of the rods, or both. In addition, the variation of the polymer entropy with twist depends on changes in both the surface area and the volume of the monolayer. Rod fluctuations perpendicular to the monolayer also play an important role in stabilising the twisting.

arXiv comment14 pages, 12 figures

References in corpus (18)

• Chiral plasmonics
• Molecular Chirality and Chiral Parameters
• freud: A Software Suite for High Throughput Analysis of Particle Simulation Data
• Confinement-Induced Liquid Crystalline Transitions and Chirality Inversion in Amyloid Fibril Cholesteric Tactoids
• Interpretation of saddle-splay and the Oseen-Frank free energy in liquid crystals
• Molecular engineering of chiral colloidal liquid crystals using DNA origami
• Entropy-driven formation of prolate and oblate cholesteric phases by computer simulations
• Entropy driven formation of a chiral liquid crystalline phase of helical filaments
• Density Functional Theory for Chiral Nematic Liquid Crystals
• Entropic forces stabilize diverse emergent structures in colloidal membranes
• Left or right cholesterics? A matter of helix handedness and curliness
• Chiral shape fluctuations and the origin of chirality in cholesteric phases of DNA origamis
• Achiral symmetry breaking and positive Gaussian modulus lead to scalloped colloidal membranes
• The isotropic-to-nematic phase transition in hard helices: theory and simulation
• Cholesteric and screw-like nematic phases in systems of helical particles
• Conformational switching of chiral colloidal rafts regulates raft-raft attractions and repulsions
• Gnomonious Projections for Bend-Free Textures: Thoughts on the Splay-Twist Phase
• Good Fibrations: Packing Rules for Diabolic Domains