275117 Investigating Polymer Relaxation in Nanochannels and Nanoslits

Wednesday, October 31, 2012: 9:06 AM
411 (Convention Center )
Yeng-Long Chen1,2,3, Jen-Fang Chang3 and Pokeng Lin3, (1)Department of Chemical Engineering, National Tsing-Hua University, Hsinchu, Taiwan, (2)Department of Physics, National Taiwan University, Taipei, Taiwan, (3)Institute of Physics, Academia Sinica, Taipei, Taiwan

We investigate polymer relaxation in nanoslits and nanochannels with the lattice Boltzmann-Brownian dynamics (LB-BD) method.  Classical theories of deGennes and Odijk predict a transition of polymer properties as the confinement height H becomes smaller than the polymer persistence length, at which the confinement strongly affects the stiffness and restricts the conformational entropy of a semi-flexible polymer such as DNA. With LB-BD, the stretch relaxation time and fluctuation correlation decay time (tr) are measured in nano-confinements of height H, from H larger than the polymer radius of gyration Rg to smaller than the polymer persistence length P. A clear transition in tr is observed for chains in nanochannels.  tr is found to have a non-monotonic dependence on H, as found in previous experimental observations [1].  In contrast, a clear transition is not observed for chains in nanoslits [2,3].  The difference between nanoslits and nanochannels may be attributed to the confinement-induced changes on chain relaxation mechanisms. Hydrodynamic interactions are found to influence the chain relaxation time, even in confinement smaller than P.

[1] W. Reisner et al., Physical Review Letters 94, 196101 (2005).

[2] PK Lin et al., Macromolecules 45, 2920 (2012).

[3] J. Tang et al., Macromolecules 43, 4368 (2010).

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See more of this Session: Thermodynamics at the Nanoscale
See more of this Group/Topical: Engineering Sciences and Fundamentals