Polymer–Metal Hybrid Material with an Ultra-High Interface Strength Based on Mechanical Interlocking via Nanopores Produced by Electrochemistry

This study fabricated polymer–metal hybrid (PMH) materials with ultrahigh strengths using an effective electrochemical treatment strategy and direct molding bonding. It is found that the bonding strength of the prepared PMH between the polymer and metal reached as high as 21.0 MPa. Characterizations revealed the formation of a new multinanoporous Al₂O₃ layer on an aluminum (Al) alloy after electrochemical treatment. The thickness of the Al₂O₃ layer was 6.2–15.3 μm, and nanopores with an average diameter of 7.8–14.3 nm were parallelly distributed throughout the whole Al₂O₃ layer. The formation of countless nanorivets allows large-area mechanical interlocking at the interface between the polymer and Al alloy, which is thought to be the key mechanism of achieving ultrahigh strength. At the optimal treatment voltage of 18 V, the maximum mechanical strength of the PMH material was obtained, and the corresponding number of the formed nanorivets was 5.75 × 10¹⁰ in theory. Also, the average size of the nanopores was 14.3 nm. Compared to the traditional chemical treatments, the electrochemical method is no doubt a more effective treatment.