TY  - JOUR
SP  - 7343
N2  - 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. 
A1  - Morrison, Greg
A1  - Hyeon, Changbong
A1  - Toan, Ngo Minh
A1  - Ha, Bae-Yeun
A1  - Thirumalai, D.
SN  - 0024-9297
PB  - American Chemical Society
UR  - http://pubs.acs.org/doi/abs/10.1021/ma071117b
IS  - 20
JF  - Macromolecules
AV  - none
TI  - Stretching Homopolymers
Y1  - 2007///
VL  - 40
EP  - 7353
ID  - eprints1814
ER  -