UV‐Triggered Polymerization, Deposition, and Patterning of Plant Phenolic Compounds

Abstract

Plant-derived phenolic compounds, rich in catechol and pyrogallol moieties, can form multifunctional coatings on various substrates following polymerization under mildly alkaline conditions. Despite many appealing features of such coatings, the difficulty to control polymerization of phenolic compounds spatially and temporally limits their number of potential applications. In this study, it is demonstrated that UV irradiation can trigger oxidative polymerization and deposition of plant-derived phenolic compounds, which opens the possibility to create 2D gradients and patterns of polyphenol coatings and control this polymerization temporally. UV-vis spectroscopy, electrospray ionization mass spectrometry, and cyclic voltammetry analyses are used to investigate the UV-induced polymerization of several plant-derived phenolic compounds including pyrogallol, tannic acid, caffeic acid, and gallic acid. Formation of polyphenol coatings on polar and nonpolar substrates after UV irradiation has been studied using water contact angle measurements, atomic force microscopy, time of flight secondary ion mass spectrometry, and X-ray photoelectron spectroscopy (XPS). The possibility to use UV-light to accelerate polymerization of phenolic compounds and perform micropatterning can extend the scope of potential applications of the large class of structurally diverse plant-derived phenolic compounds.

Phenolic Building Blocks for the Assembly of Functional Materials

“…Angewandte Chemie International Edition REVIEW be used for surface modification via oxidative selfpolymerization. [121,122] Instead of using basic pH, UV radiation can induce the oxidative self-polymerization of phenolic compounds [123] and has been used to construct patterned thin films (Figure 6e-g). [124] As the field grows through expanding the library of building blocks and different methodologies, a wide variety of new materials and applications are expected to emerge.…”

Silicate‐Phenolic Networks: Coordination‐Mediated Deposition of Bioinspired Tannic Acid Coatings

“…[13] Efforts have, therefore,b een made to induceacontinuous coating formation by slow conversion of Fe 2 + to Fe 3 + ,y et with limited efficiency. [16] The stability of TA in alkaline conditions is, however,l imited, and the auto-oxidation by dissolved oxygen leads to uncontrolled degradation of TA andp recipitation of polymeric byproducts. [16] The stability of TA in alkaline conditions is, however,l imited, and the auto-oxidation by dissolved oxygen leads to uncontrolled degradation of TA andp recipitation of polymeric byproducts.…”

“…[14] Induced oxidative polymerization is based on the spontaneous auto-oxidative polymerization of polyphenols in an alkaline environment [3c, 15] or triggered by UV-light. [16] The stability of TA in alkaline conditions is, however,l imited, and the auto-oxidation by dissolved oxygen leads to uncontrolled degradation of TA andp recipitation of polymeric byproducts. [17] Recently,w er eported an alternative deposition method using silicic acid (Si aq ), which enables ac ontinuous TA coating formation on titaniums urfaces.…”

An effective surface modification of UHMWPE fiber for improving the interfacial adhesion of epoxy resin composites

“…The pristine UHMWPE fiber exhibited the absorption peaks at 2908 cm −1 related to methylene nonsymmetric stretch vibration, 2853 cm −1 related to methylene symmetric stretch vibration, 1468 cm −1 related to methylene nonsymmetric angle vibration, and 714 cm −1 related to methylene swing in plane vibration. Compared with pristine fiber, the spectrum of UHMWPE fiber modified by TA displayed some notable changes including a peak at 3400 cm −1 from phenolic OH stretching vibration of TA and a peak at 1668 cm −1 from stretching vibration of CO bond. In addition, the new peaks appeared at 1500, 1405, 1362 — , and 1186 cm −1 , which were attributed to CC and phenolic CO stretching vibrations.…”