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221. Radke, W.; Müller, A.H.E.: Synthesis and Characterization of comb-shaped polymers by SEC with on-line light scattering and viscometry detection, Macromolecules 38, 3949, published on the web March 30, 2005 (2005) | |
Abstract: Comb-shaped polystyrenes with UV-labeled side chains were synthesized
and analyzed by SEC with on-line light scattering and viscometry
detection. The introduction of the UV label allows for a
model-independent determination of the number of grafts within each SEC
slice and therefore the calculation of the expected contraction
factors, g = g,br>/g,lin>
and g = [η]br/[η]lin
and . Using molecular weight sensitive detectors the contraction
factors were determined experimentally and compared to the expected
ones. It was found that the experimentally determined g-values are
larger than the ones calculated based on Gaussian chain assumption.
Therefore, the calculation of the number of branches based on
theoretically expected contraction factors is not feasible. Attempts to
include corrections for excluded volume effects failed. For the
exponent e of the relationship g°=°gε a value close to
ε°=°1 was found, in contradiction with the expectations from the
Flory-Fox and
Zimm-Kilb relations. It was observed that the intrinsic viscosities of
the combs are close to the intrinsic viscosities of the parent backbone
polymer itself, allowing to use this empirical relationship for the
determination of the amounts of grafts present in the polymer.
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