Free-energy effects in single-molecule polymer crystals

The paper presents extensive MD simulations of the crystallization process of a single polyethylene chain with N = 500 monomers. It is shown that the folding process involves intermediate metastable crystalline states, in analogy with the experiments, and ends up in a equilibrated. i.e. not kinetically selected, lamella with ten stems of approximately equal length, arranged into a regular, hexagonal pattern. The free-energy landscape is presented and the different energy and entropy contributions, the latter mostly due to surface rearrangements, discussed. (c) 2006 Elsevier B.V. All rights reserved.