Mechanical characterization of polydopamine-assisted silver deposition on thiol-ene polymer substrates

The purpose of this study was to characterize the mechanical properties of polydopamine-adhered silver on a mechanically tailorable thiol-ene system. Polydopamine and silver coatings were deposited on a variety of commercially available polymer substrates through a simple dip-coat process. The polydopamine forms a thin uniform adhesive layer, while the silver was prescribed to deposit in a discontinuous manner with a nanoparticle base-layer covering the full surface and micron-sized particle clusters adhered sporadically on top. Mechanical tensile testing was performed to characterize the durability of the polydopamine-adhered silver coating. Coated nylon, high-density polyethylene (HDPE), and thiol-ene substrates showed no signs of degradation or delamination in the polydopamine-adhered silver coating up to 30% tensile strain. Peel tests were performed on both commercial polymers as well as a tailorable thiol-ene system. Results support the hypothesis that polydopamine adhesion is increased by the presence of functional groups in the substrate. Antimicrobial tests showed significant resistance to bacterial growth by the silver coating when compared to bare substrate. In summary, with the addition of functional groups in the substrate polymer makeup, the adhesion strength of polydopamine-adhered silver coatings can be increased to create a mechanically durable and adhesively robust silver coating that maintains the antimicrobial properties associated with silver films.