Oxidant-induced plant phenol surface chemistry for multifunctional coatings: Mechanism and potential applications

Plant-inspired polyphenols are capable of forming substrate-independent coatings for versatile functionalization via oxidative self-polymerization in an alkalescent aqueous solution. However, shortcomings like low uniformity and lengthy reaction times discourage their large-scale implementations. In this work, we report a benign surface modification method for the highly effective, inexpensive construction of catechol (CA) coatings using sodium periodate (SP) as a trigger. Compared with recent progress in polyphenol coatings, our strategy achieved by far the fastest superhydrophilic modification rate ever reported. UV-vis spectroscopy, atomic force microscopy (AFM) and ellipsometry are used to gain insights into the reaction kinetics of oxidant-triggered polymerization and deposition of CA. SP-assisted CA films with good homogeneity were efficiently deposited on various dense and porous substrates. Ultimately, the unprecedentedly superhydrophilic/underwater superoleophobic coating layer was applied on the initially hydrophobic polyvinylidene fluoride (PVDF) membrane, endowing the porous membrane with extremely high pure water permeability, favorable heavy metal adsorption ability, and outstanding oil/water separation performance. Due to the chemical versatility of CA, we envision that this novel coating technique holds significant potentials in tailoring the surface properties of different materials for a wide range of applications.