Metal Ions in Polydopamine Coatings Enhance Polymer-Metal Adhesion

Area of Science:

• Materials Science
• Polymer Science
• Surface Chemistry

Background:

• Strong bonding at polymer-metal interfaces is vital for advanced lightweight thermoplastic composite structures.
• Interfacial adhesion challenges in polymer-metal systems necessitate tailored molecular interactions for improved performance.

Purpose of the Study:

• To optimize interfacial adhesion between polycarbonate (PC) and titanium (Ti) using metal ion-containing polydopamine (M+PDA).
• To investigate the effects of different metal ions and deposition methods on adhesion energy.
• To gain insights into the surface morphology and chemistry of M+PDA films.

Main Methods:

• Fabrication of M+PDA thin films on titanium wires via postdeposition and codeposition methods.
• Comolding titanium wires with a PC matrix to create pullout samples.
• Evaluation of interfacial energy of adhesion (Ga) using pullout tests.
• Surface characterization using Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and solid-state nuclear magnetic resonance (NMR).

Main Results:

• Fe3+PDA and Fe2+PDA coatings significantly increased the interfacial energy of adhesion (Ga) between Ti and PC.
• Codeposition of Cu2+ with dopamine (DA) showed an increasing trend in Ga with increasing Cu2+:DA ratio, plateauing at 1:1.
• The concentration of metal ions (M+) did not influence Ga values, irrespective of the deposition method.

Conclusions:

• Metal ion-containing polydopamine coatings, particularly with Fe3+ or Fe2+, are effective in enhancing interfacial adhesion between polycarbonate and titanium.
• The study provides a deeper understanding of the surface chemistry and morphology of M+PDA films, crucial for designing robust polymer-metal interfaces.
• This research contributes to the development of improved lightweight thermoplastic composite structures through optimized interfacial bonding.