Adhesive Interactions of Polyurethane Monomers with Native Metal Surfaces

作者：Nies Christophe; Wehlack Carsten; Ehbing Hubert; Dijkstra Dirk J; Possart Wulff^*

来源：The Journal of Adhesion, 2012, 88(8): 665-683.

DOI：10.1080/00218464.2012.682865

• Chemical adhesion
• IR external reflection absorption spectroscopy
• Methylene diphenyl diisocyanate
• Native metal surfaces
• Polypropylene ether triol

Understanding of fundamental adhesion is a key issue for bonding, polymer composites, and coatings. In this study, diluted solutions of polyurethane monomers (methylene diphenyl diisocyanate isomer mixture-MDI, polypropylene ether triol-PPET) are exposed to the native surfaces of Au, Al, and Cu. The adsorption state of the molecules (from multi-to sub-monolayers) is investigated in situ by infrared external reflection absorption spectroscopy (IR-ERAS). A sequence of solvent rinsing steps helps to distinguish physisorbed from chemisorbed molecules. PPET sticks very weakly to the metals. The spectra reveal a bulk-like state. MDI adsorbs weakly on Au but the spectra differ significantly from the bulk state. On Al and Cu, MDI establishes strong adhesion. Rich new spectral features indicate a probably chemical nature of adhesion, and a specific structure in the neighboring adsorbate layer. However, detailed final conclusions on the adhesion mechanisms must not be derived without appropriate quantum mechanical modeling.

• 出版日期2012