Surface energy of strained amorphous solids

• Published in: Nature communications Vol. 9; no. 1; pp. 982 - 6
• Main Authors: Schulman, Rafael D., Trejo, Miguel, Salez, Thomas, Raphaël, Elie, Dalnoki-Veress, Kari
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 07-03-2018; Nature Publishing Group; Nature Portfolio
• Subjects: 132/122; 639/301/119/544; 639/301/923/1030; 639/766/119/544; Amorphous materials; Condensed Matter; Contact angle; Elastomers; Fluid flow; Humanities and Social Sciences; Incompressible flow; Interfaces; Materials Science; multidisciplinary; Physics; Science; Science (multidisciplinary); Solids; Surface energy; Surface properties
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-03346-1

Surface stress and surface energy are fundamental quantities which characterize the interface between two materials. Although these quantities are identical for interfaces involving only fluids, the Shuttleworth effect demonstrates that this is not the case for most interfaces involving solids, since their surface energies change with strain. Crystalline materials are known to have strain-dependent surface energies, but in amorphous materials, such as polymeric glasses and elastomers, the strain dependence is debated due to a dearth of direct measurements. Here, we utilize contact angle measurements on strained glassy and elastomeric solids to address this matter. We show conclusively that interfaces involving polymeric glasses exhibit strain-dependent surface energies, and give strong evidence for the absence of such a dependence for incompressible elastomers. The results provide fundamental insight into our understanding of the interfaces of amorphous solids and their interaction with contacting liquids.
Whether or not amorphous solids exhibit strain-dependent surface energies, like those of crystalline materials, is still a matter of debate. Here, Schulman et al. monitor the contact angle of droplets on strained polymeric glasses and elastomers, which directly probes energy variation at the interfaces.