relation: http://eprints.imtlucca.it/1814/
title: Stretching Homopolymers
creator: Morrison, Greg
creator: Hyeon, Changbong
creator: Toan, Ngo Minh
creator: Ha, Bae-Yeun
creator: Thirumalai, D.
subject: QD Chemistry
description: Force-induced stretching of polymers is important in a variety of contexts. We have used theory and simulations to describe the response of homopolymers, with N monomers, to an external force (f ) in good and poor solvents. In good solvents and for sufficiently large N we show, in accord with scaling predictions, that the mean extension along the f axis 〈Z〉 ∼ f for small f and 〈Z〉 ∼ f 2/3 (the Pincus regime) for intermediate values of f. The theoretical predictions for 〈Z〉 as a function of f are in excellent agreement with simulations for N = 100 and 1600. However, even with N = 1600, the expected Pincus regime is not observed due to the breakdown of the assumptions in the blob picture for finite N. We predict the Pincus scaling in a good solvent will be observed for N ≳ 105. The force-dependent structure factors for a polymer in a poor solvent show that there is a hierarchy of structures, depending on the nature of the solvent. For a weakly hydrophobic polymer, various structures (ideal conformations, self-avoiding chains, globules, and rods) emerge on distinct length scales as f is varied. A strongly hydrophobic polymer remains globular as long as f is less than a critical value fc. Above fc, an abrupt first-order transition to a rodlike structure occurs. Our predictions can be tested using single molecule experiments. 
publisher: American Chemical Society
date: 2007
type: Article
type: PeerReviewed
identifier:   Morrison, Greg and Hyeon, Changbong and Toan, Ngo Minh and Ha, Bae-Yeun and Thirumalai, D.  Stretching Homopolymers.  Macromolecules, 40 (20).  pp. 7343-7353.  ISSN 0024-9297      (2007)  
relation: http://pubs.acs.org/doi/abs/10.1021/ma071117b
relation: 10.1021/ma071117b