Effect of solvent quality on the conformations of a model comb polymer(2/3)
Date Issued
2004-05-17
Date
2004-05-17
Author(s)
DOI
922214E002003
Abstract
The effect of solvent quality on the equilibrium structure of a densely-branched comb polymer is investigated
based on the structure factor analyses by off-lattice Monte Carlo simulations. Firstly, theta temperature ( θ∞)
must be determined to identify the solvent condition. We locate the characteristic temperature, θ A,(N), at which
the second virial coefficient vanishes and the transition temperature, θ R(N), at which radius of gyration, Rg, of
the chain varies most rapidly with temperature, i.e. 0 /
2 2 =
R
dT R d g θ . N represents the total number of
monomers of a comb. As N ∞, θ A and θ R coincide to a point that is identified as the true theta temperature ( θ∞).
The structure factors of the main chain, the side chain, and the whole polymer are calculated, respectively. It is
found that at T= θ∞, the structural factors S(qRg) for the overall comb polymers match quite well with those of
their Gaussian counterparts. When T< θ∞, the overall comb polymer assumes collapsed conformations, similar to
a homogeneous sphere. However, the structure factor of the side chain indicates that it always remains in an
expanded state regardless of the solvent condition. It is attributed to the strong interactions between side chains.
The same effect leads to enhanced rigidity of the main chain in comparison to the linear chain, as clearly
observed from the rescaled Kratky plot
Subjects
Monte Carlo simulations
comb polymers
second virial coefficient
structural factor
Publisher
臺北市：國立臺灣大學化學工程學系暨研究所
Type
report
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