Tannic Acid‐Inspired Star‐Like Macromolecules via Temporally Controlled Multi‐Step Potential Electrolysis

Abstract

Inspired by tea stains, a plant polyphenolic‐based macroinitiator is prepared for the first time by partial modification of tannic acid (TA) with 2‐bromoisobutyryl bromide. In accordance with the “grafting from” methodology, a naturally occurring star‐like polymer with a polar gallotannin core and a hydrophobic poly(n‐butyl acrylate) side arms is synthesized via a simplified electrochemically mediated ATRP (seATRP), utilizing multiple‐step potential electrolysis. To investigate the kinetics of the electrochemical catalytic process triggered by reduction of Cu(II) or Fe(III) catalytic complex in the presence of the multifunctional initiator, cyclic voltammetry measurements are conducted. The naturally derived tannin macromolecule shows narrow MWDs (Đ = 1.57). Moreover, solvolysis of the star polymer to cleave the side arms and characterize them indicates that all chains grow to the same length (homopolymers with Mw/Mn <1.17), which confirms the well‐controlled seATRP. The structure of the obtained TA‐based systems is characterized microscopically (AFM) and spectroscopically (1H NMR, FT‐IR). Atomic force microscopy measurements precisely determine the diameters of the obtained star polymers (19.7 ± 3.3 nm). These new star polymers may find biomedical applications as drug delivery systems and antifouling or antimicrobial coatings.

Synthesis of Riboflavin‐Based Macromolecules through Low ppm ATRP in Aqueous Media

“…The analysis of the chains length of polymer brushes was conducted by cleaving the PBA chains attached to the riboflavin core by acid solvolysis according to the procedure described in reference . The resulting polymers were analyzed by DMF GPC, determining apparent M n and Ð of PBA chains.…”

“…It can be triggered by the introduction of a reducing compound, for example, radical initiator in initiators for continuous activator regeneration (ICAR) ATRP, chemical reducing agents (e.g., glucose, ascorbic acid, hydrazine), and metallic silver in activators regenerated by electron transfer (ARGET) ATRP, zerovalent metals (Fe 0 , Cu 0 ) in supplemental activator and reducing agent (SARA) ATRP. Alternatively, an external stimuli such as a reducing current in electrochemically mediated ATRP ( e ATRP) and simplified electrochemically mediated ATRP ( se ATRP), light in photo‐induced ATRP (photo‐ATRP), or mechanical forces in mechanically induced ATRP (mechano‐ATRP) and in ultrasonication‐induced ATRP (sono‐ATRP) can be applied . Electrochemistry offers additional opportunity to catalyst recycle, eliminates needs for chemical reducing agents, provides temporal control during the process, and extends polymerization to aqueous media .…”

Preparation of hydrophobic tannins‐inspired polymer materials via low‐ppm ATRP methods

“…Before the solvolysis, the final polymer samples from each reaction were dialyzed against methanol for 1 week with the use the dialysis membrane MWCO 1kD (see GPC traces before and after solvolysis in Figure S6). The detachment of the star polymer arms was conducted by acid solvolysis according to the previously described procedure …”

“…The reduction of catalyst complex amount is based on its continuous regeneration due to incorporation of an additional redox cycle using an appropriate reducing agent or external stimulus . These techniques include, among others, supplemental activator and reducing agent (SARA) ATRP utilizing metallic copper as a reducing agent, activator regeneration by electron transfer (ARGET) ATRP using elemental silver to effective reduction of the catalyst complex in the higher oxidation state, what also limits side reactions, and hence by‐products, moving to a more environmentally friendly method using an external stimulus to receive activators—simplified electrochemically mediated ATRP ( se ATRP), which uses an electric current without the necessity of introducing any additional chemical compound making this technique extremely pure in context to the current state of art …”

“…Recently, Pranantyjo et al reported the surface coating material composed of TA grafted with cationic [2‐(methacryloyloxy)ethyl]trimethylammonium chloride, zwitterionic 2‐methacryloyloxyethyl phosphorylcholine, and N ‐(3‐sulfopropyl)‐ N ‐(methacryloxyethyl)‐ N , N ‐dimethylammonium betaine to receive antifouling properties in the two‐step route, firstly synthesized TA initiation primer with three brominated initiation sites, subsequently using surface‐initiated ATRP to incorporate appropriate monomer into the structure of the coating material . Next, our group developed TA‐inspired biomacromolecules characterized by 20 PBA arms using se ATRP technique with an emphasis on the electrochemical characterization of the received macroinitiator and investigation of the electrochemically mediated process in the preparation of tannins star‐shaped polymers . Matyjaszewski et al fully functionalized TA with α‐bromoisobutyryl bromide to receive degradable star‐shaped polymers .…”