Synthesis of naturally-derived macromolecules through simplified electrochemically mediated ATRP

Abstract

The flavonoid-based macroinitiator was received for the first time by the transesterification reaction of quercetin with 2-bromoisobutyryl bromide. In accordance with the “grafting from” strategy, a naturally-occurring star-like polymer with a polar 3,3',4',5,6-pentahydroxyflavone core and hydrophobic poly(tert-butyl acrylate) (PtBA) side arms was synthesized via a simplified electrochemically mediated ATRP (seATRP), utilizing only 78 ppm by weight (wt) of a catalytic CuII complex. To demonstrate the possibility of temporal control, seATRP was carried out utilizing a multiple-step potential electrolysis. The rate of the polymerizations was well-controlled by applying optimal potential values during preparative electrolysis to prevent the possibility of intermolecular coupling of the growing polymer arms. This appears to be the first report using on-demand seATRP for the synthesis of QC-(PtBA-Br)5 pseudo-star polymers. The naturally-derived macromolecules showed narrow MWDs (Đ = 1.08–1.11). 1H NMR spectral results confirm the formation of quercetin-based polymers. These new flavonoid-based polymer materials may find applications as antifouling coatings and drug delivery systems.

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

“…ATRP—one of the most versatile reversible‐deactivation radical polymerization (RDRP) procedures—has a few essential features, including narrow molecular weight distribution (MWD, M w / M n , Ð ) and control over molecular weight (MW) of prepared macromolecules, and also the possibility to site‐specific incorporation of functionalities . Originally, traditional ATRP systems required high catalyst concentration (1000–10 000 ppm) to maintain the activity during the polymerization.…”

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ATRP-one of the most versatile reversible-deactivation radical polymerization (RDRP) procedures [13,14] -has a few essential features, including narrow molecular weight distribution (MWD, M w /M n , Ð) and control over molecular weight (MW) of prepared macromolecules, and also the possibility to site-specific incorporation of functionalities. [15][16][17][18][19] Originally, traditional ATRP systems required high catalyst concentration (1000-10 000 ppm) to maintain the activity during the polymerization. Significant progress has been recently achieved allowing to diminish the concentration of Cu-based catalysts to parts per million (ppm) due to an application of additional activator regeneration redox step.

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“…Alternatively, an external stimuli such as a reducing current in electrochemically mediated ATRP (eATRP) [27][28][29][30] and simplified electrochemically mediated ATRP (seATRP), [31][32][33] light in photo-induced ATRP (photo-ATRP), [34,35] or mechanical forces in mechanically induced ATRP (mechano-ATRP) [36] and in ultrasonication-induced ATRP (sono-ATRP) can be applied. [37,38] Electrochemistry offers additional opportunity to catalyst recycle, [18,39] eliminates needs for chemical reducing agents, [40] provides temporal control during the process, [27] and extends polymerization to aqueous media. [41][42][43][44] Environmentally friendly aqueous systems provide better thermal control and higher rate of polymerization; however, they also bring a few challenges.…”

Temporally Controlled Ultrasonication‐Mediated Atom Transfer Radical Polymerization in Miniemulsion

“…Due to the obvious advantages including excellent control over molecular weight (MW), narrow dispersity (MWD, M w /M n , Ð), [1][2][3][4][5] and ability to incorporate functionality in specific macromolecule place, [6][7][8][9] the most representative RDRP technique is atom and hydrophobic catalyst (dual-catalyst mechanism) in the context of using electric current as a reducing stimulus; [29] moving to single-catalyst approach with only strongly hydrophilic catalyst resulted in excellent control during poly(n-butyl acrylate) polymerization. [23] It was also applied with the use of ascorbic acid as a reducing agent in ARGET ATRP receiving precisely controlled PBA and PBMA macromolecules with different architecture [23] and in photoinduced ATRP under UV light providing temporal control over the polymerization.…”

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

“…The procedure involves the simple task of adding initiator functionality to the reactive hydroxyl and phenolic groups by the esterification reaction. The prepared multifunctional macroinitiator is functionalized in the next step by incorporating well‐defined polymeric arms . Moreover, ATRP stands out other advantages including preparation of well‐defined hybrid composites with narrow molecular weight distributions (MWDs) and control over molecular weight (MW) .…”