Integration of Cation–π Interactions with Polyphenols for Super‐Hydrophilic Coatings

Abstract

Inspired by natural channels, graphene oxide membrane has been used to separate metals or solvents due to the different affinity between aromatic group and metal ions. [6] In addition, cation-π interactions have been used for the engineering underwater adhesive materials. [7] Mussel-inspired chemistry has demonstrated its versatility for multifunctional coatings based on the oxidized poly merization of dopamine (DA) and noncovalent interactions. [8] The cation-π interaction is one of the primary forces for the intermolecular assembly of DA, which is indicated by the formation and disassembly of the polydopamine (PDA) coatings at different pH. [9] The disassembled PDA coatings could reassemble into films in the presence of cation (e.g., K + ) for surface coatings, where cation types significantly influence the strength of cation-π interactions. In addition, the structure of aromatic groups also affects the strength of cation-π interactions, which is verified by detecting the adhesion force of polymers with aromatic side groups and poly-L-lysine. [10] Compared to DA, polyphenols (e.g., tannic acid, TA) have been demonstrated their superiority to functionalize substrates with colorless coatings or coordinate with metal ions for the engineering of films and particles. [11] However, the integration of cation-π interactions with polyphenols is rarely reported for surface functionalization.Herein, we report a facile approach for the engineering of super-hydrophilic coatings via the integration of cation-π interactions with polyphenols and investigate the effect of the types of cations and polyphenols on the hydrophilicity and stability of the coatings. As a result, coatings obtained from TA and tetramethylammonium (TMA) demonstrate super-hydrophilic property, which can be resistant against acid (pH 3) and alkali (pH 14). The polyphenol coatings based on cation-π interactions also show their superiority for oil-water separation, self-cleaning, and anti-foggy applications. The phenolic coatings based on the integration of cation-π interactions provide a promising strategy for surface engineering and functionalization. Results and DiscussionTo investigate the influence of pyrogallol and catechol on the cation-π interactions, TA and DA were used as the electron-rich π agents to bind cations (i.e., Na + and K + ) for copper mesh coatings (denoted as DA, DA-Na, DA-K, TA, TA-Na, and TA-K copper meshes). Scanning electron microscopy (SEM) images showed Cation-π interaction is one of the most important noncovalent interactions found in biosystems, which has attracted great interests for the engineering of functional materials. In this work, one-step assembly of super-hydrophilic coatings via surface modification with polyphenols and cations is reported based on cation-π interactions. Hydrophilicity of surface coatings is tunable by the variation of cations based on the different affinity between polyphenols and cations. Copper meshes coated with tannic acid and tetramethylammonium demonstrate super-hydrophilicity and high stab...

Mussel-Inspired Cation−π Interactions: Wet Adhesion and Biomimetic Materials

“…Another type of superhydrophilic coating was prepared on a hydrophobic copper mesh via one-step self-assembly of catechol-containing molecules with cations, where cation−π interactions played a dominant role in the adhesion process. 37 Various catechol-containing molecules, such as dopamine and tannic acid (TA), along with different cations including Na + , K + , and tetramethylammonium (TMA), were examined. It was observed that TA-based coatings displayed lower water contact angles compared to dopamine-based coatings.…”

“…Furthermore, the quaternary ammonium groups in CPHA demonstrated antimicrobial activity, which could effectively inhibit bacterial invasion from the outer side without disrupting the ecological balance of healthy human skin. Another type of superhydrophilic coating was prepared on a hydrophobic copper mesh via one-step self-assembly of catechol-containing molecules with cations, where cation−π interactions played a dominant role in the adhesion process . Various catechol-containing molecules, such as dopamine and tannic acid (TA), along with different cations including Na + , K + , and tetramethylammonium (TMA), were examined.…”

A Mesostructure Multivariant‐Assembly Reinforced Ultratough Biomimicking Superglue

“…[11][12][13] This bioglue, based on polyphenols, exhibits robust adhesion by the synergistic interaction of various intermolecular forces, playing a crucial role in enhancing researchers' understanding of interactions in soft materials. [14,15] By learning and imitating this polyphenol-based bioglue, researchers have made progress in synthesizing a range of materials such as nanoparticles, [16,17] hydrogels, [18,19] bioadhesives, [20][21][22][23][24][25] and so on. These advancements have resulted in breakthroughs in high-performance adhesion, antimicrobial properties, and tissue regeneration.…”