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Effects Of Surfactants And Polymers On Advancing And Receding Contact Angles
Published 1986 · Materials Science
Abstract Advancing and receding contact angles of several aqueous surfactant and polymer solutions were measured on paraffin wax (PF), poly(methyl methacrylate) (PMMA), poly(ethylene terephthalate) (PET), and polyethylene (PE). The polymers used included hydroxypropylcellulose (HPC), hydroxypropylmethylcellulose (HPMC), poly(vinyl pyrrolidone) (PVP), poly(ethylene glycol) (PEG) and hydroxyethylcellulose (HEC). Plots of adhesion tension, γLVcosθ, versus surface tension, γLV, were used to analyze factors influencing the ability of the polymers to affect advancing contact angles, relative to surfactants. Whereas all polymers and surfactants exhibited predictable and nonspecific effects on PF, the more hydrophobic polymers HPC and HPMC and all surfactants on PMMA, PET, and PE were less efficient in reducing the contact angle than a pure liquid with the same surface tension. These observations were interpreted in terms of the relative adsorption of solute at the solid—liquid and liquid—vapor interfaces. Receding contact angle measurements revealed no specific effects on PF for any solute, nor did the more hydrophilic polymers show specific effects on any solid. However, the hydrophobic polymers, HPC and HPMC, at all concentrations, and all surfactants above a certain concentration, caused zero degree receding angles to occur on all solids except PF, even when advancing angles were quite high. These effects are attributed to the specific nature of polymer and surfactant adsorption at the solid surface.