Some Remarks on the Components of the Liquid Surface Free Energy

Abstract

Measurements of the contact angle for water, glycerol, formamide, and ethylene glycol on paraffin, polytetrafluoroethylene (PTFE), polyethylene (PE), polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), and polyethylene terephthalate, for diiodomethane on PE, PVC, PMMA, and PET, and for a series ofn-alkanes fromn-heptane ton-hexadecane on PTFE were made. On the basis of the contact angles obtained on paraffin, PTFE, and PE the Lifshitz-van der Waals components of the glycerol, formamide, and ethylene glycol surface free energy were determined. Next, by using the contact angle values of water, glycerol, formamide, ethylene glycol, and diiodomethane, the values of the electron-acceptor and electron-donor parameters of the acid-base components of the surface free energy of glycerol, formamide, and ethylene glycol were calculated and compared with the values taken from the literature. It was found that the Lifshitz-van der Waals component of the formamide surface free energy and the electron-acceptor and electron-donor parameters of the glycerol, formamide, and ethylene glycol surface free energy determined in the above-mentioned way differ from those determined by van Osset al.and by Lee. They are closer to those determined on the basis of interfacial tension measurements. Using the newly determined components and parameters it was found that PVC has an electron-acceptor character in contrast to an electron-donor character in the literature.