Regensburg 2016 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 42: Focus: Multiscale Simulations for Soft Matter: The Challenge of Dynamics (joint session CPP/DY, organized by CPP)

DY 42.3: Vortrag

Mittwoch, 9. März 2016, 15:30–15:45, H51

Thermodynamics of polymer nematics: particle-based simulations versus mean-field calculations — •Cristina Greco, Kurt Kremer, and Kostas Daoulas — Max Planck Institute for Polymer Research, Mainz, Germany

Conjugated liquid crystalline (LC) polymers have emerged as promising materials for organic electronics. Predicting their large-scale morphology requires the implementation of mesoscale models. The statistical mechanics of such models is often addressed using mean-field (MF) approaches. These have been very successful in polymer physics and are attractive because of their computational efficiency and straightforward description of thermodynamic properties. For LC polymers, however, deviations between MF predictions and experimental results have been reported, e.g. for the molecular weight dependence of the nematic-isotropic transition. The question then arises: are the discrepancies due to the MF approximation or do they reveal fundamental limitations of the model, e.g. transferability?

To address this issue, we consider a model representing polymer nematics as worm-like chains interacting through soft anisotropic potentials and investigate its phase behaviour by (i) MF calculations based on partial enumeration of conformations, (ii) Monte Carlo simulations. In the latter, accurate free energies are obtained via a special thermodynamic integration scheme which avoids thermodynamic singularities. By comparing the results of the two methods, we can evaluate the effect of fluctuations and local correlations on the macroscopic behaviour.