1. Unité de Physique et de Chimie des Hauts Polymères, Université catholique de Louvain, Place Croix du Sud 1, B-1348 Louvain-la-Neuve, Belgium; Centre for Supramolecular and Macromolecular Chemistry, Department of Chemistry, University of Warwick, Gibbert Hill Road, Coventry CV4 7AL, United Kingdom; and School of Chemistry, University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh EH9 3JJ, United Kingdom