Simulations of self-assembling supramolecular wires using patchy molecules
Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)Abstract
We present a highly flexible, coarse grained model to simulate the selective and directionally dependent interactions driving supramolecular self-assembly without an explicit solvent. To this purpose we describe molecules as (mostly) rigid assemblies of hard spheres, interacting via patches of attraction whose interaction strength depend on their respective orientation; stiffer patches cause a larger loss of orientational freedom upon forming a bond. Our main focus will be on the experimentally and theoretically studied case of discotic molecules P. van der Schoot et al. Langmuir 16 (2000), 10076 that aggregate via $\pi$-bond stacking, and due to the hydrophobic effect, into both randomly ordered as well as helically twisted wires. Our Monte Carlo simulations allow one to relate the macroscopic quantities such as the free energy of a bond, and the aggregation volume fraction to the details of the microscopic interactions. We show that the stiffness of a reversible bond is equivalent to the interaction volume in equilibrium polymerization theory, and discuss the deviation from ideal behavior at high temperatures. Furthermore we address how the alignment of diamagnetic aggregates by a magnetic field influences the aggregation statistics differently for high and low temperature.