posted on 2020-01-29, 14:35authored byJia-Wei Yeh, Alessandro Taloni, K. K. Sriram, Jie-Pan Shen, Der-You Kao, Chia-Fu Chou
Macromolecules
in an entangled environment are constrained to wriggle
predominantly along a confining tube, giving rise to the so-called
reptation or tube-like motion. While the principles of polymer physics
were well developed to understand its conformational dynamics, the
quantitative characterization of the tube diameter and resulting reptation
remains an open question. Here, using highly confined parallel plate
geometry nanoslits down to sub-30 nm, we directly observe reptation
in a one-dimensional (1D) confined nanoenvironment. We provide a quantitative
analysis scheme, by introducing the segmental tangential vector and
its associated correlation function, to characterize the strand reptation
and connect it to the confinement degree. Our analysis shows that
the amplitude of the transverse fluctuations (the virtual 2D “tube”)
exhibits the typical scaling of fluctuating interfaces, contact lines,
or charge density waves, with a roughness exponent, which depends
on the slit height. Our results are shown to lead to less rough DNA
profiles in shallower nanoslits. We anticipate our analysis to be
a starting point for a more detailed understanding of the relationship
between polymer physics and other nonequilibrium physical systems.