Laccase from Trametes versicolor catalyzes the controlled radical polymerization of N-vinylimidazole, yielding narrowly dispersed, metal-free polymers.
Reversible-deactivation radical polymerizations (controlled radical polymerizations) have revolutionized and revitalized the field of polymer synthesis. While enzymes and other biologically derived catalysts have long been known to initiate free radical polymerizations, the ability of peroxidases, hemoglobin, laccases, enzyme-mimetics, chlorophylls, heme, red blood cells, bacteria, and other biocatalysts to control or initiate reversible-deactivation radical polymerizations has only been described recently. Here, the scope of biocatalytic atom transfer radical polymerizations (bioATRP), enzyme-initiated reversible addition-fragmentation chain transfer radical polymerizations (bioRAFT), biocatalytic organometallic mediated radical polymerizations (bioOMRP), and biocatalytic reversible complexation mediated polymerizations (bioRCMP) is critically reviewed and the potential of these reactions for the environmentally friendly synthesis of precision polymers, for the preparation of functional nanostructures, for the modification of surfaces, and for biosensing is discussed. Biologically derived catalysts, such as enzymes or their cofactors, represent an attractive alternative to conventional polymerization catalysts because they are non-toxic, biodegradable, and derived from sustainable resources. Moreover, enzymes can display high stereo-, regio-, or chemo-selectivity, 1 while working under mild conditions. They have been extensively explored for the in vitro synthesis of polymers, 1-3 e.g. by ring opening polymerization (ROP) 4-5 or polycondensation. 6-7 Several enzymes can also mediate free radical polymerizations. 8-9 For example, laccases use oxygen to create radicals on phenols, which then undergo radical coupling polymerization. 10 This reaction has been used since ancient times to create traditional Japanese lacquerware from the sap of the lacquer tree Rhus vernicifera that contains the monomers and the enzyme. 11 Enzymatic radical polymerizations are also involved in the biosynthesis of lignin 12 and of melanin. 13 Not surprisingly, radicalproducing enzymes have also been explored in synthetic polymer chemistry, for example to polymerize vinyl monomers (e.g. acrylates and acrylamides), 8, 14 anilines, 15 phenols 2, 16-17 and lignols. 3, 18-19 While peroxidases and other heme proteins, as well as laccases, can initiate free radical polymerizations using peroxides and oxygen, respectively, 8-9 until recently it was unknown that biocatalysts can also control or initiate radical polymerizations in very similar ways to conventional catalysts for reversible-deactivation radical polymerizations (also termed controlled radical polymerizations (CRPs). 20-23 Here, we review the nascent field of biocatalytic controlled radical polymerizations (bioCRP) and critically discuss the potential of these novel enzymatic polymerizations in applications such as polymer synthesis, development of functional nanostructures, and biosensing.
Derivatives of chlorophyll were investigated as both catalysts and comonomers to generate well-defined polymers with narrow dispersities under AGET ATRP conditions.
In this work, the influence of carbon nanotubes (CNTs) on the self‐assembly of nanocomposite materials made of cylinder‐forming polystyrene‐block‐poly(ethylene‐butylene)‐block‐polystyrene (SEBS) is studied. CNTs are modified with polystyrene (PS) brushes by surface‐initiated atom transfer radical polymerization to facilitate both their dispersion and the orientation of neighboring PS domains of the block copolymer (BCP) along modified CNT‐PS. Dynamic rheology is utilized to probe the viscoelastic and thermal response of the nanoscopic structure of BCP nanocomposites. The results indicate that nonmodified CNTs increase the BCP microphase separation temperature because of BCP segmental confinement in the existing 3D network formed between CNTs, while the opposite holds for the samples filled with modified CNT‐PS. This is explained by severely retarded segmental motion of the matrix chains due to their preferential interactions with the PS chains of the CNT‐PS. Moreover, transient viscoelastic analysis reveals that modified CNT‐PS have a more pronounced effect on flow‐induced BCP structural orientation with much lower structural recovery rate. It is demonstrated that dynamic‐mechanical thermal analysis can provide valuable insights in understanding the role of CNT incorporation on the microstructure of BCP nanocomposite samples. Accordingly, the presence of CNT has a significant promoting effect on microstructural development, comparable to that of annealing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.