Simulations of Polymer Cyclization by Brownian Dynamics
Received March 20, 1997 Revised Manuscript Received July 28, 1997 Abstract: The dynamic characteristics of polymers in dilute solution, such
as the end-to-end distance
relaxation time, Download the full text:
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m, and the time of diffusion-controlled
cyclization, a, were studied using Brownian
dynamics simulations. The major goal was to estimate the effect of
the impenetrability of the chain
backbone on the dynamic properties. We compared several models of
polymer chains: phantom ones
with and without excluded volume and a nonphantom model with excluded
volume. The hydrodynamic
interaction between chain segments was not taken into account. The
impenetrability of a chain is found
to have a small effect on the magnitude of m. For
sufficiently long chains, m exceeded the value
for
phantom chains by factor of 1.5. The ratio
a/m remained the same for the phantom and
nonphantom
models. On the other hand, the excluded volume effect changed the
dependence of m on the chain contour
length, in accordance with the known theoretical conclusions. In
addition, the presence of excluded volume
caused a 2-fold increase of the scaling factor between a
and m for sufficiently long chains. This
scaling
factor and, consequently, a appeared to be reciprocally
proportional to the reaction radius R. When
the
reaction radius is close to the statistical segment length
l, a was estimated as a =
(l/R)m, where the
coefficient is equal to 1.3 ± 0.2 and 2.6 ± 0.3 for chains
without and with excluded volume, respectively.
