Thermodynamics of polymer nematics described with a worm-like chain model: particle-based simulations and SCF theory calculations

Polymer liquid crystals, apart from traditional applications as high strength materials, are important for new technologies, e.g. Organic Electronics. Their studies often invoke mesoscale models, parameterized to reproduce thermodynamic properties of the real material. Such top-down strategies require advanced simulation techniques, predicting accurately the thermodynamics of mesoscale models as a function of characteristic features and parameters. Here a recently developed model [1] describing nematic polymers as worm-like chains interacting with soft directional potentials is considered. We present a special thermodynamic integration scheme delivering free energies in particle-based Monte Carlo simulations of this model, avoiding thermodynamic singularities. Conformational and structural properties, as well as Helmholtz free energies are reported as a function of interaction strength. They are compared with state-of-art SCF calculations [2] invoking a continuum analog of the same model, demonstrating the role of liquid-packing and fluctuations. [1] P. Gemünden and K.Ch. Daoulas, Soft Matter 2015, 11, 532; [2] Y. Jiang and J.Z.Y. Chen, Macromolecules 2010, 43, 10668.