Regensburg 2022 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 49: Polymer and Molecular Dynamics, Friction and Rheology

CPP 49.3: Talk

Friday, September 9, 2022, 12:00–12:15, H39

Measuring Volume Exclusion on Single Polymer Chains Diffusing in Solution — •Tobias Thalheim and Frank Cichos — Peter Debye Institute for Soft Matter Physics, Leipzig University, Germany

Excluded volume effects in single polymer chains occur due to long-range interactions of distant segments in the chain which cannot pass through each other entailing a strong influence of the static as well as the dynamic behavior of the polymer. Various theoretical descriptions were thus devised to incorporate these effects in the interpretation of experimental outcomes. A theory by Schäfer and Krüger incorporating this real-polymer phenomenon predicts a distribution function which describes the total segment density about an individual polymer's center of mass. This distribution function augments the picture of an ideal Gaussian chain by correction functions that account for volume exclusion and which were derived in the framework of renormalization groups. Although this permits the assessment of the role of volume exclusion for single chains in contrast to usual accesses via scaling theories or ensemble measurements, this theory has never been tested before. We report on experiments including two types of freely-diffusing double-stranded DNA molecules that utilize Schäfer's and Krüger's theory to investigate these effects. We show that for short λ-DNA molecules volume exclusion is of minor importance, whereas long T4-DNA molecules exhibit prominent volume exclusion. Furthermore, we employ a thermophoretic trapping method to test this theory on single compressed polymers subjected to a virtual harmonic potential.