Colorless polydopamine coatings for creating functional interfaces

Since the emergence of surface modification techniques, including polydopamine (PDA) layers using a single deposition process that is based on the oxidative self-polymerization of dopamine (DA), the number of studies concerning the functionalization of material surfaces via PDA coating has increased. While PDA is simple to apply to cover onto various kinds of substrates, most of conventional PDA layers show considerable dark brown coloration, restricting their use for some practical applications such as, optical materials, cosmetics, and diagnostic test materials. In this chapter, we provide an overview of our research of a colorless PDA layer containing atom transfer radical polymerization (ATRP) initiator prepared by the reaction of DA with 2-bromoisobutyryl bromide (BiBB). The synthesized colorless PDA/BiBB2 layer ([BiBB]/ [DA] = 2) was successfully covered onto various types substrates, e.g., glass plates, flexible polypropylene films, filter papers, silica particles, and polymer particles. Then, the surface-initiated ATRP was conducted to create bioand smart-interfaces (Hierarchically structured coating). Furthermore, preparation of polymer brush based materials, colored particles, and raspberry-like particles based on colorless PDA coating were also investigated.