Direct measurement of surface energies of polymers-contact mechanics based approach

This paper summarizes the direct measurements of surface energies of a variety of polymers. The Johnson, Kendall, Roberts theory (JKR theory) of contact mechanics relates the adhesion induced deformation and pull-off force to the thermodynamic work of adhesion. This principle has been used for the direct measurement of surface and interfacial energies. The polymer films which have been examined are poly (ethylene terephthalate) [PET], polyethylene [PE], poly (vinyl cyclohexane) [PVCH], polystyrene [PS], poly (methyl methacrylate) [PMMA], poly (4-methyl 1-pentene) [TPX], and poly (vinyl pyridine) [PVP]. The contact mechanics determined surface energies have been compared with surface energies inferred from contact angle data. No theory used for the inference of surface energies of polar polymers from contact angle data was useful in predicting the surface energies measured from contact mechanics. Of the examined theories, the original Good-Girifalco approach, which accounts for liquid-solid interactions, comes closest to predicting the contact mechanics determined surface energies.