POS2-0464
Surface Free Energy Change of Poly(dimethylsiloxane) under Elongational Deformation
Topic
S2. High-End Characterization/Polymer Physics/Properties
When and Where
Sep 29, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Hae Jung SON
Boseok KANG
Presenter(s)
Lynn Bekki (Kyushu University)
Co-Author(s)
Abstract
Polymer-based flexible devices are used under deformation, so understanding the structure and physical properties of polymers under deformation is essential not only from a scientific viewpoint but also for rational materials design. At surfaces and interfaces, polymer chains are in contact with dissimilar media and therefore exist in different energy states from those in the bulk, so that the aggregation states of polymer chains are substantially different from those in the bulk as well. Accordingly, these surface and interfacial aggregation states under deformation should differ from those in the bulk. In this study, we aimed to clarify the surface aggregation states under deformation using the surface free energy (g) as an indicator of their changes. PDMS was prepared by mixing Sylgard 184 base and curing agent (10:1 weight ratio) and curing at 423 K for 10 min. Sheets were cut into dumbbell shapes. Contact angle measurements under tensile strain were conducted at room temperature using a tensile tester and a contact angle meter. Pure water and diiodomethane were used as probe liquids. Upon reaching the target strain, the liquids were deposited and contact angles were recorded perpendicular to the elongational direction after 1 s. Contact angles of water and diiodomethane decreased with increasing tensile strain. The g value, calculated via the Owens–Wendt method, increased with strain. Because g is defined as the derivative of the free energy with respect to a change in surface area and related to entropy reflecting conformational freedom, its increase would indicate that chain conformations at the surface decreased. Thus, the result indicates that tensile deformation induces chain orientation, reducing possible conformations. This demonstrates that deformation decreases the conformational freedom of polymer chains even at surfaces, resulting in increased g.
