Material-Independent Surface Chemistry beyond Polydopamine Coating

Abstract

Conspectus Various methods have been developed in surface chemistry to control interface properties of a solid material. A selection rule among surface chemistries is compatibility between a surface functionalization tool and a target material. For example, alkanethiol deposition on noble metal surfaces, widely known as the formation of a self-assembled monolayer (SAM), cannot be performed on oxide material surfaces. One must choose organosilane molecules to functionalize oxide surfaces. Thus, the surface chemistry strictly depends on the properties of the surface. Polydopamine coating is now generally accepted as the first toolbox for functionalization of virtually any material surface. Layer-by-layer (LbL) assembly is a widely used method to modify properties of versatile surfaces, including organic materials, metal oxides, and noble metals, along with polydopamine coating. On flat solid substrates, the two chemistries of polydopamine coating and LbL assembly provide similar levels of surface modifications. However, there are additional distinct features in polydopamine. First, polydopamine coating is effective for two- or three-dimensional porous materials such as metal–organic frameworks (MOFs), synthetic polyolefin membranes, and others because small-sized dopamine (MW = 153.18 u) and its oxidized oligomers are readily attached onto narrow-spaced surfaces without exhibiting steric hindrance. In contrast, polymers used in LbL assembly are slow in diffusion because of steric hindrance due to their high molecular weight. Second, it is applicable to structurally nonflat surfaces showing special wettability such as superhydrophobicity or superoleophobicity. Third, a nonconducting, insulating polydopamine layer can be converted to be a conducting layer by pyrolysis. The product after pyrolysis is a N-doped graphene-like material that is useful for graphene or carbon nanotube-containing composites. Fourth, it is a suitable method for engineering the surface properties of various composite materials. The surface properties of participating components in composite materials can be unified by polydopamine coating with a simple one-step process. Fifth, a polydopamine layer exhibits intrinsic chemical reactivity by the presence of catecholquinone moieties and catechol radical species on surfaces. Nucleophiles such as amine and thiolate spontaneously react with the functionalized layer. Applications of polydopamine coating are exponentially growing and include cell culture/patterning, microfluidics, antimicrobial surfaces, tissue engineering, drug delivery systems, photothermal therapy, immobilization of photocatalysts, Li-ion battery membranes, Li–sulfur battery cathode materials, oil/water separation, water detoxification, organocatalysts, membrane separation technologies, carbonization, and others. In this Account, we describe various polydopamine coating methods and then introduce a number of chemical derivatives of dopamine that will open further development of material-independent surface chemistry.

Oxidation‐Mediated Kinetic Strategies for Engineering Metal–Phenolic Networks

“…Theabove observations provide valuable insights into the mechanism of MPN formation by the OMC assembly method. First, the molecular TA-Fe III complexes adsorb on the surface owing to the adhesion provided by TA, [15] followed by the formation of at hin MPN layer on the substrate,a s shown in Figure 1e.S imultaneously,t he precursors form metal-phenolic nuclei in solution. Owing to the slower assembly kinetics of this method, the self-correction of the dynamic coordination bonds potentially increases and subsequent premature termination decreases,which leads to the formation of nuclei complexes that can continuously grow into particles in solution.…”

Rapid preparation of polydopamine coating as a multifunctional hair dye

“…15,16 Polydopamine (PDA), a black pigment naturally occurring in melanin, has been demonstrated to deposit on virtually all types of materials, including inorganic and organic surfaces, with high adhesiveness and a controllable thickness. [17][18][19] PDA also exhibits many remarkable features in electrical, optical, and heat transfer applications as well as striking biocompatibility. [20][21][22][23] However, few reports have focused on the black color of PDA, which is an attractive property for applications in cosmetics.…”

Functional Macromolecule‐Enabled Colloidal Synthesis: From Nanoparticle Engineering to Multifunctionality

“…The adhesive and rigid PDA is a versatile “glue” that, theoretically, can be coated on various inorganic nanomaterials with different shapes and dimensions . Recently, Zhou et al used PDA to fix a magnetic nanoparticle assembly that aligned into linear arrays under a homogeneous external magnetic field, resulting in PDA‐coated 1D magnetic nanochains ( Figure a) .…”