Thursday May 13th 2010
Presentation Room «N. Koumoutsou»

Prof. Jean Pierre Hansen

Department of Chemistry, University of Cambridge, Cambridge, United Kingdom

Multi-blob representations of semi-dilute polymer solutions

P. Flory was the first to suggest a coarse-grained representation of polymers in dilute solutions as single "blobs" or "soft colloids" interacting via effective pair potentials between their centres of mass. The idea has since been substantially developed by our group and others, to describe long polymers in good or poor solvent, as well as diblock copolymers in selective solvent.

We will show how the idea can be generalized to semi-dilute solutions, where polymer coils strongly overlap, by introducing a systematic multi-blob representation. The effective interactions between blobs are determined by a rigorous inversion procedure of structural data obtained from Monte-Carlo simulations of fully atomistic models. The weakness of the effective interactions allows very efficient simulations of large samples of high molecular weight polymers and copolymers, as well as accurate analytic predictions based on a generalized random phase approximation. The multi-scale coarse-graining strategy has been extended to investigate the self-assembly of concentrated diblock copolymer solutions into micellar and other microphases. The effective blob representation has also been applied to long polymers grafted on a planar substrate; we have discovered a new stretching regime in the limit of very high grafting densities.