Insights into the Thermal Expansion of Amorphous Polymers

We investigated the thermal expansion of amorphous polystyrene (PS) and poly­(methyl methacrylate) (PMMA) homopolymers using the temperature dependence of spatial electron-density correlations. The strong and broad X-ray interference maxima arising from inter- and intramolecular correlation distance...

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Bibliographic Details
Published in:ACS macro letters 2024-11, Vol.13 (11), p.1490-1494
Main Authors: Eim, Sungoh, Jo, Seungyun, Kim, Junsu, Park, Sungmin, Lee, Dongjun, Russell, Thomas P., Ryu, Du Yeol
Format: Article
Language:English
Subjects:
Homopolymer
Molecular distance
Thermal volume expansion
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Summary:We investigated the thermal expansion of amorphous polystyrene (PS) and poly­(methyl methacrylate) (PMMA) homopolymers using the temperature dependence of spatial electron-density correlations. The strong and broad X-ray interference maxima arising from inter- and intramolecular correlation distances were distinct, maintaining their shape during the heating of the samples to 250 °C. Three maxima characteristic of electron density correlations between the backbones, substituents along the chain, and repeat-units were observed. A remarkable temperature dependence was identified in the largest correlation distances arising from the intermolecular interactions. Based on the temperature dependence of the correlation distances, the coefficients of molecular expansion were very close to the coefficients of thermal expansion. This study provides a simple yet accurate way to correlate macroscopic volume expansions with the molecular expansion obtained from wide-angle X-ray scattering (WAXS) data.
ISSN:2161-1653
2161-1653
DOI:10.1021/acsmacrolett.4c00574