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Ind. Eng. Chem. Res., 2013, 52 (25), pp 8616–8621.
Jilin Zhang , Yuxi Zhao , Matthew R. Dubay , Steven J. Severtson, Larry E. Gwin , Carl J. Houtman.
Department of Bioproducts and Biosystems Engineering, University of Minnesota, 2004 Folwell Avenue, St. Paul, Minnesota 55108, United States and
Franklin International, 2020 Bruck Street, Columbus, Ohio 43207, United States and
Forest Products Laboratory, USDA, One Gifford Pinchot Drive, Madison, Wisconsin 53726, United States.
Abstract
Comparisons of properties are made for pressure-sensitive adhesives (PSAs) generated via emulsion polymerization using both conventional and reactive emulsifiers. The emulsifiers are ammonium salts of sulfated nonylphenol ethoxylates with similar chemical structures and hydrophilic–lipophilic balances. The polymerizable surfactant possesses a reactive double bond at its phenyl ring allowing for participation in free-radical polymerization reactions. Incorporation of the polymerizable surfactant into the adhesive polymer was confirmed via reverse-phase liquid chromatography. Surfactant distributions in PSA films were characterized using confocal Raman microscopy and contact angle measurements. Increasing conventional surfactant concentrations in emulsion polymerization reactions resulted in proportional increases in concentrations at the surfaces of latex-cast films. No surface enrichment of adhesive films was observed when reactive emulsifiers were employed. Variations in measured depth profiles and contact angles are consistent with observed performance properties, for example, tack, peel strength, and shear times. Increasing concentrations of conventional surfactants decreased adhesive performance, while adhesives generated with polymerizable surfactants showed little or no such decreases in film performance properties. It is concluded that the polymerizable surfactant is bound in the adhesive in such a way that its migration to film surfaces during drying and formation is inhibited, preventing degradation of adhesive performance.
Copyright © 2013 American Chemical Society
