Measurement of interfacial adhesion between glassy polymers using the JKR method

The surface and interfacial energies of polymers are measured using the JKR‐type experiments. A novel method has been developed to prepare samples of glassy polymers for adhesion measurements. A thin layer of a polymer is coated on the surface of an O 2 ‐plasma modified cross‐linked poly(dimethylsiloxane) [PDMS] spherical cap resulting in the formation of a composite. Using the JKR theory, the surface energies of polystyrene [PS] and poly(methyl methacrylate) [PMMA] are determined from the measurements of the contact radius as a function of applied load. The results of the JKR‐type experiments are compared to adhesion measurements done using the surface forces apparatus (SFA). Adhesion hysteresis was observed for PS‐PS contact as well as PMMA‐PMMA contact. However, no hysteresis was observed for PDMS‐PDMS, PDMS‐PS, and PDMS‐PMMA contacts. The exact origin of the hysteresis is not clear at present. The current evidence suggests that hysteresis is due to rearrangement of the interface during contact.