Related Experiment Video
Updated: May 27, 2026

Studying Large Amplitude Oscillatory Shear Response of Soft Materials
Published on: April 25, 2019
Single-molecule elasticity measurements of the onset of excluded volume in poly(ethylene glycol)
Andrew Dittmore1, Dustin B McIntosh, Sam Halliday
1Materials Department, University of California, Santa Barbara, California 93106, USA.
Abstract:
A polymer must reach a certain size to exhibit significant excluded-volume interactions and adopt a swollen random-walk configuration. We show that single-molecule measurements can sense the onset of swelling by modulating the effective chain size with force: as the force is reduced from a large value, the polymer is first highly aligned, then a Gaussian coil, then finally a swollen chain, with each regime exhibiting a distinct elasticity. We use this approach to quantify the structural parameters of poly(ethylene glycol) and show that they vary in the expected manner with changes in solvent.
Related Concept Videos
Determination of Molar Masses of Polymers II
Size-Exclusion Chromatography
Silica particles offer advantages such as rigidity,...
Polymers: Molecular Weight Distribution
Molecular Weight of Step-Growth Polymers
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...

