International Journal of Adhesion and Adhesives
2021
Effect of PAA-induced surface etching on the adhesion properties of ZnO nanostructured films
D. MEINDERINK; C. KIELAR; O. SOBOL; L. RUHM; F. RIEKER; K. NOLKEMPER; A.G. ORIVE; O. OZCAN; G. GRUNDMEIER

Abstract

Zinc oxide – polymer interfaces are known to exhibit interesting properties regarding molecular adhesion. This work is aimed at the investigation of the effect of the morphology and surface chemistry on the macroscopic adhesion of a model epoxy-based adhesive to nanorod (ZnO NR) and nanocrystalline (ZnO NC) ZnO-modified surfaces. Both ZnO films have been prepared using hydrothermal synthesis on hot-dip galvanized steel (HDG) surfaces by varying the precursor chemistry in order to control the film morphology. Poly (acrylic acid) (PAA) was used to improve the interfacial adhesion by modifying the morphology and surface chemistry of ZnO nanostructured films. The strong interaction of PAA from a dilute and neutral aqueous solution with the ZnO nanocrystallites was shown to significantly improve the interfacial adhesion by means of a nanoetching process. It was shown that the wet peel-forces correlate well with the considered morphology and surface chemistry.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS)

… As control, SC and ZnO NC samples were spray-coated with the same PAA solution (3.64 μM PAA (250.000 g/mol) in water at pH 7 adjusted with solid NaOH) and analyzed via ToF-SIMS. The spray coating process of aqueous PAA solutions has been described elsewhere [39]. A commercial spray coater (ND-SP 11/4 Precision Spray Coater, Nadetech Innovations S.L., Spain) with an installed hot-plate was used.

Keywords: ZnO nanorods; Nanocrystalline ZnO films; Adhesion by mechanical interlocking; Poly(acrylic acid); Morphology control; Interfacial stability