To determine whether this regime, where the chains are so covered as to prevent further folding, is relevant for the aggregation observed here, the fraction of monomers in aggregates that interacted with other monomers in any other chain was calculated. This variable, N total /N, defined in Fig. , gives the total number of monomer-monomer interactions between one chain and any other chain. In the poor and intermediate solvents, this quantity was in excess of 80% of the full chain length (about 16 monomers for 20mers; Fig. ) after 4 µs of simulation, indicating that chains that are in aggregates are almost fully covered by other chains. Although the small regions where chains are not overlapped may still be able to fold, the aggregates will be substantially stiffer than the single chains, and effectively stuck in an extended state, from which the further build up of extended rod-like structures can occur.