What is it about?

By measuring shear wave propagation across glassy polystyrene and rubbery polybutadiene bilayer films, we have demonstrated the emergence of a long range 200 nm gradient in local modulus when the interface between the glassy and rubbery polymer domains is formed. This work provides support and a possible new mechanism for understanding long range profiles in local glass transition temperature Tg that have previously been measured in these systems.

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Why is it important?

Interfaces impact the properties of glasses over surprisingly large length scales, which has important implications for developing nanoscale devices involving polymers. This work suggests a new mechanism for how local dynamics in glasses may be coupled over long distances by the way sound waves can propagate across the material, reflecting at or transmitting across interfaces, and interacting with the vibrational spectrum of density fluctuations.


Once we started to realize that sound wave propagation across the system was likely interacting with density fluctuations in the vibrational density of states, many other studies in the literature dating back decades started to come together.

Connie Roth
Emory University

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This page is a summary of: Development of broad modulus profile upon polymer–polymer interface formation between immiscible glassy–rubbery domains, Proceedings of the National Academy of Sciences, December 2023, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2312533120.
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