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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 29: Gels, Polymer Networks and Elastomers II
CPP 29.1: Talk
Wednesday, March 20, 2024, 15:00–15:15, H 0106
Structural characterization of model gels at preparation conditions and at swelling equilibrium — •Michael Lang and Reinhard Scholz — Leibniz Institut für Polymerforschung Dresden, Hohe Straße 6, 01069 Dresden, Germany
We use large scale computer simulations of star polymer model gels to separate the static and the dynamic contributions of the scattering intensity I(q), allowing to determine the correlation length ξ of the corresponding polymer solution and the static correlation length Ξ combining several properties of the denser cross-link blobs. The correlation length ξ can incorporate parts of the form factor of the stars for polymer volume fractions around the overlap condition of the stars, affecting a determination of ξ from the scattering data. At swelling equilibrium, the cross-link motion is confined within a volume comparable to the size of the somewhat denser cross-link blob. Since the cross-link blob size scales ∝ξ, we measure Ξ∝ξ for our near ideal model networks. The confined motion of the cross-links implies a Gaussian shape for the static contribution. At swelling equilibrium, the dynamic part of the scattering intensity Idyn(0) related to the solution-like correlation lengths is almost identical to the scattering intensity Istat(0) of the static part. At preparation conditions, Istat(0)/Idyn(0) decays with a power law following the polymer fraction of the cross-link blobs. Here, the larger volume available volume for cross-link motion stands out for increasing polymer volume fraction, reducing the concentration dependence of Ξ.
Keywords: scattering; polymer networks; correlation length; elasticity