The modification of surface properties of isotactic polypropylene (it.PP) has attracted much attention in fundamental science and industrial applications. Primer treatment is a promising methods that is employed to overcome the poor adhesive property of it. PP. In this study, we examined the primer effect of the cobalt complexes, cobalt (II) acetylacetonate Co(acac)(2) and cobalt (III) acetylacetonate Co(acac)(3), from the perspectives of adhesive strength, curing process, surface structure, affinity between substrate and adhesive, morphology and interfacial thickness. The results obtained explain the increased adhesive strength between an isotactic polypropylene substrate and a cyanoacrylate adhesive. In particular, the interfacial regions were evaluated as "interphase" by nano-Raman scattering microscopy and transmission electron microscope-energy-dispersive X-ray spectroscopy. The region is expanded by applying Co(acac)(2) primer as the adhesive strength increased. The Co(acac)(2) primer caused the increased adhesive property with the enhancement of molecular interaction, chemical affinity, and mutual diffusion. (c) 2018 Elsevier Ltd. All rights reserved.