Second-virial theory for shape-persistent living polymers templated by discs

• Published in: arXiv.org 2021-11
• Main Authors: Marina Torres Lázaro, Aliabadi, Roohollah, Wensink, Henricus H
• Format: Article
• Language: English
• Subjects: Additives; Bonding strength; Fractions; Liquid crystals; Liquid phases; Molecular weight distribution; Phase separation; Polymers; Supramolecular polymers
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2111.07639

Living polymers composed of non-covalently bonded building blocks with weak backbone flexibility may self-assemble into thermoresponsive lyotropic liquid crystals. We demonstrate that the reversible polymer assembly and phase behavior can be controlled by the addition of (non-adsorbing) rigid colloidal discs which act as an entropic reorienting ``template" onto the supramolecular polymers. Using a particle-based second-virial theory that correlates the various entropies associated with the polymers and discs, we demonstrate that small fractions of discotic additives promote the formation of a polymer nematic phase. At larger disc concentrations, however, the phase is disrupted by collective disc alignment in favor of a discotic nematic fluid in which the polymers are dispersed anti-nematically. We show that the anti-nematic arrangement of the polymers generates a non-exponential molecular-weight distribution and stimulates the formation of oligomeric species. At sufficient concentrations the discs facilitate a liquid-liquid phase separation which can be brought into simultaneously coexistence with the two fractionated nematic phases, providing evidence for a four-fluid coexistence in reversible shape-dissimilar hard-core mixtures without cohesive interparticle forces. We stipulate the conditions under which such a phenomenon could be found in experiment.