Statistical mechanics of aggregation and crystallization for semiflexible polymers

¹  Institut für Theoretische Physik and Centre for Theoretical Sciences (NTZ), Universität Leipzig Postfach 100 920, D-04009 Leipzig, Germany, EU
²  Max-Planck-Institut für Polymerforschung - Ackermannweg 10, D-55128 Mainz, Germany, EU
³  Institut für Festkörperforschung, Theorie II, Forschungszentrum Jülich - D-52425 Jülich, Germany, EU

Corresponding authors: junghans@mpip-mainz.mpg.de m.bachmann@fz-juelich.de Wolfhard.Janke@itp.uni-leipzig.de

Received: 27 March 2009
Accepted: 3 August 2009

Abstract

By means of multicanonical computer simulations, we investigate thermodynamic properties of the aggregation of interacting semiflexible polymers. We analyze a mesoscopic bead-stick model, where nonbonded monomers interact via Lennard-Jones forces. Aggregation turns out to be a process, in which the constituents experience strong structural fluctuations, similar to peptides in coupled folding-binding cluster formation processes. In contrast to a recently studied related proteinlike hydrophobic-polar heteropolymer model, aggregation and crystallization are separate processes for a homopolymer with the same small bending rigidity. Rather stiff semiflexible polymers form a liquid-crystal–like phase, as expected. In analogy to the heteropolymer study, we find that the first-order–like aggregation transition of the complexes is accompanied by strong system-size–dependent hierarchical surface effects. In consequence, the polymer aggregation is a phase-separation process with entropy reduction.