Large-area mechanical interlocking via nanopores: Ultra-high-strength direct bonding of polymer and metal materials

Abstract

This study employed an effective and economical strategy of chemical treatments to achieve the direct bonding of polymer and metal materials. The bonding strength of the prepared polymer-metal structure could easily reach 20 MPa or more, which far exceeded the data that used to bond polymers and metals in other ways. The results of characterizations confirmed that the large-area mechanical interlocking of nanopores between polymer and metal was the essential reason for obtaining excellent performance. The countless nanopores were formed on the surface of the Al alloy due to the chemical reactions after treatments. Therefore, the countless nano-rivets could be naturally formed at the interface. Besides, a good infiltration of the metal surface caused by nanopores also had a contribution, because the contact angle was only 21.9° after treatments. We also confirmed that the size of nanopores was directly related to the mechanical strength of the polymer-metal structure. Bonding strength was >20.0 MPa when the average diameter was 30.3 nm. From SEM, EDX, and XPS, the chemical mechanism and the principle for each treatment step were proposed. This simple strategy will have potential application prospects in the field of automobile, shipping, and electronics where polymer-metal structures are needed.