Greener electrochemical plating of ABS polymer with unprecedented adhesion via hierarchical micro–nanotexturing

Electrochemical plating is the most widely used coating process for metalizing commodity polymers, such as acrylonitrile–butadiene–styrene (ABS). Conventionally, ABS polymer is pretreated in concentrated sulfochromic acid solution before plating to develop a highly porous surface topography that ensures coating adhesion. Unfortunately, using chromic acid produces extremely hazardous chemical waste, which costs manufacturers millions of dollars in fines. This study proposes a threefold greener route by employing a newly developed in-mold patterning of polymeric parts before plating. We hot-embossed micron-sized dimples on the ABS polymer and acid-etched it for as short as 1 min to obtain a hierarchical micro–nanotextured surface. The coating adhesion on such surfaces appeared to be two times higher as compared to the conventional electroplating, while the etching time was reduced three times. Microscopic characterization of the fracture surfaces revealed that the adhesion strength at the hierarchically structured interface exceeded the strength of the ABS polymer, causing a cohesive crack in the polymer far below the interface when peeling the plated metallic film. These results imply that the use of toxic acids in the electroplating industry can be drastically reduced by the proposed hybrid preparation method without sacrificing the coating quality.