Effect of Interfacial Adhesion on Viscoelastic Relaxation Processes in Thin Polymer Film Indentation
Peter M. Johnson, Christopher Stafford
Polymer coatings are dependent on strongly bonded buried interfaces to maintain adhesion and protective properties over long application lifetimes. In this work, we detail the detection of buried interfaces with deviations from perfect bonded or perfect slip interfaces using surface indentation on thin films with large contact areas. The interfacial interactions between photopolymerized methacrylate films and a glass substrate were tailored using silane chemistry to create an interface that either crosslinked with the polymer network or easily released. Creep compliance measurements on the poly(methacrylate) films were compared with predicted contact measurements for literature models of ideal interfaces. Non-ideal contributions from interfacial effects were detected during experiments with high confinement. These effects changed dependent on the polymer network structure and polymer/substrate interface, with fluorinated interfaces exhibiting up to a 30% change from an ideal bonded indentation due to the presence of a weak interface. The ability to probe the response of a buried interface under low indentation loads is attractive for testing and validating the interfacial properties of coatings and films, and this approach could be used to interrogate the fidelity of an interface in critical areas such as corrosion protection and encapsulation.
and Stafford, C.
Effect of Interfacial Adhesion on Viscoelastic Relaxation Processes in Thin Polymer Film Indentation, ACS Applied Materials and Interfaces, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=905404
(Accessed February 23, 2024)