Strategies for Metallizing and Electroplating Biodegradable PLA

With environmental awareness in societies, bioplastics continue to receive increasing attention and utilization rate. Polylactic acid (PLA) is one of the most important biopolymers in the market today, owing to its high strength and relative ease of forming. Unlike the common structural, fossil fuel-based plastics, such as Acrylonitrile-Butadiene-Styrene (ABS), the surface of PLA cannot be readily metallized in preparation for electroplating using the conventional plating-on-plastic (POP) process. This partially limits the wider use of the material for functional and decorative applications. In this research study, we systematically explored three strategies for metallizing the surface of PLA, namely, (A) chemical etching and palladium activation technique, (B) polyelectrolyte multilayers (PEMs) and Ag nanoparticle deposition technique, and (C) Ag conductive painting technique. PLA samples, prepared by Fused Deposition Modelling (FDM) 3D-printing technique, were metallized by various techniques followed by electroless deposition and electroplating of copper layers. The study was performed comparatively with respect to the ABS surface. The samples microstructures, chemical distributions, and plating characteristics were assessed with optical and scanning electron microscopy. The adhesion of the metallic coatings was analyzed using scratch test and tape test. Although uniform deposition of copper layers on PLA surfaces could be achieved using all three metallizing methods under investigation, the three methods were found to provide different degrees of benefits with respect to deposition rate, surface uniformity, and process simplicity.