Adhesion Properties of Self-Polymerized Dopamine Thin Film

We report an experimental study of the adhesion properties of polydopamine thin films and their bonding behavior on polymer, glass and metal surfaces. Dopamine is able to adsorb onto all surfaces and self-polymerize into a thin hydrophilic film. Dynamic contact angle measurements revealed a large contact angle hysteresis between advancing and receding angles and a possible hydration layer when exposed to water. Polydopamine-coated surfaces in air are relatively inert having a low self-adhesion compared with polydimethylsiloxane elastomer surfaces, reflecting the nonconformal, glassy nature of polydopamine thin films. The dopamine aqueous solution was found able to bond two rigid surfaces (e.g. aluminum and glass) but it might not be suitable for joining soft or flexible polymer surfaces as polydopamine films are glassy and subject to internal cracks induced by the mismatch of elastic modulus. The research findings provide insights into the potential application of dopamine self-polymerization for adhesive bonding or joining of dissimilar materials.