Narrow molecular weight resins by a free-radical polymerization process

Georges, Michaël K.; Veregin, Richard P. N.; Kazmaier, Peter M.; Hamer, Gordon K.

doi:10.1021/ma00063a054

Cited by 2,021 publications

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“…In fact, it is very similar to the inifer system but the species are not initiators per se and require the use of true radical initiators. These initiators can be added in controlled amounts like in the polymerization with alkoxyamines as transfer agents 29 . The role of the initiator may be played by impurities or even by the product of decomposition of transfer agents (alkyl dithiocarbamates) 16 .…”

Section: R2n-c(s)-s-s-c(s)-nr2 2r2n-c(s)-s (18)mentioning

confidence: 99%

“…Some of the best controlled polymers obtained by radical polymerization are prepared with preformed alkoxyamines or those prepared in situ 29 . Alkoxyamines alone are inefficient initiators, unless at very high temperatures, but they might react easily with radicals.…”

Section: R2n-c(s)-s-s-c(s)-nr2 2r2n-c(s)-s (18)mentioning

confidence: 99%

“…"R 2 N-C(S) SP' +n + -P R 2 N-C (S) So + P'n-Pm (29) This type of transfer may also lead to the formation of block copolymers with the macromolecular dithiocarbamate. Thus, block copolymers may not be formed via typical chain extension process but rather via coupling of a growing polyB with a polyA-terminated with dithiocarbamate moiety 31 .…”

Section: R2n-c(s)-s-s-c(s)-nr2 2r2n-c(s)-s (18)mentioning

confidence: 99%

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"Living" radical polymerization. 1. Possibilities and limitations

Greszta¹,

Mardare²,

1994

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Section: R2n-c(s)-s-s-c(s)-nr2 2r2n-c(s)-s (18)mentioning

confidence: 99%

Section: R2n-c(s)-s-s-c(s)-nr2 2r2n-c(s)-s (18)mentioning

confidence: 99%

Section: R2n-c(s)-s-s-c(s)-nr2 2r2n-c(s)-s (18)mentioning

confidence: 99%

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"Living" radical polymerization. 1. Possibilities and limitations

Greszta¹,

Mardare²,

1994

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“…Controlled radical polymerization [nitroxide-mediated radical polymerization (NMRP), [25][26][27] atom transfer radical polymerization (ATRP), [28][29][30] etc. ], which requires neither ultra pure solvents and reagents, nor rigorous exclusion of oxygen and water, and can be carried out in bulk, solution, suspension, and emulsion, would be an ideal technique to synthesize well-controlled MJLCPs, such as a variety of star, superbranched, graft, block, and other complex architectures.…”

Section: Introductionmentioning

confidence: 99%

Jacketed polymers: Controlled synthesis of mesogen‐jacketed polymers and block copolymers

Gao

Fan

Shen

et al. 2008

J. Polym. Sci. A Polym. Chem.

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The controlled radical polymerization of mesogen‐jacketed liquid crystalline polymers has triggered great interests in synthesis of complex structures as well as well‐defined linear homopolymers with controlled molecular weight and narrow molecular weight distributions. This review highlights the synthetic strategies of controlled radical polymerization of linear homopolymers, star polymers, superbranched polymers, graft polymers, block copolymers, star block copolymers, and so on. The employed living methods include nitroxide‐mediated radical polymerization and atom transfer radical polymerization. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 319–330, 2009

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“…16 Numerous compounds containing the nitroxide radical have been synthesized and characterized by EPR, including thionitroxides generated from reactions of nitroso-compounds and thiyl radical. 17 These N-aryl or alkyl, N-thioalkyl nitroxides undergo bimolecular decompositions, a pathway not available in protein-bound species.…”

mentioning

confidence: 99%

Thionitroxides, RSNHO^•: The Structure of the SNO Moiety in “S-Nitrosohemoglobin”, A Possible NO Reservoir and Transporter

Zhao

Houk

2006

J. Am. Chem. Soc.

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Considerable evidence suggests that the S-nitrosation of cysteine residues, thought to regulate the activities of many proteins, is involved in the uptake and intracellular trafficking of NO. 1 Indeed, to absorb the neutral NO with thiols, a redox reaction is needed to form Snitrosothiols (RSNOs). [1][2][3] A structure of S-nitrosocysteine in hemoglobin proteins was first reported by Arnone and coworkers in 1998. 4a Interestingly, the resulting protein structure obtained under nonbiological conditions (NO pressure, anaerobic) exhibits unexpected C-S-N-O dihedral angles of 88° and -76° for Cys93 of β1 and β2 subunits. The crystallographic results contradict the planar geometries of all RSNOs in small molecule crystallographic data, 5 and from quantum mechanical calculations. 6 Recently, Arnone et al. refined the X-ray data again and reported that the electron density of the SNO-Cys98(F9)β could not be fit with a planar syn or an anti S-nitrosothiol model. They found C-S-N-O dihedral angles between 70° and 90° for SNO-Cys93(F9)β1 and SNO-Cys93(F9)β2. (Fig. 1) 4b To explain this, they proposed that a N-centered radical, Cys-S-N·-OH, was present and stabilized by hydrogen bonding with Val98. Such a radical was previously proposed as an intermediate in reactions of NO with thiols. 7 However, the SNO moiety in the Cys93(F9)β2 subunit is unlikely to be stabilized in this way, because the shortest O---O distance between the oxygen atom of the studied SNO species and the nearest oxygen of Lys144 is about 3.84 Å, a distance too long for significant OH---O hydrogen bonding interactions.By contrast, Montfort and coworkers have reported that the nitric oxide transport protein, nitrophorin cNP, 8 couples reduction and oxidation of a heme moiety with reversible Snitrosation of a cysteine residue (PDB: 1Y21). This S-nitrosothiol species has a C-S-N-O dihedral angle of 0°, coinciding with a planar CSNO geometry in small molecule crystallographic data. The cysteine sulfide coordinating to ferric heme is the key to the Snitrosothiol formation in this protein. Unlike nitrophorins, the NO-bound cysteine in hemoglobin is 10 Å (Fe---S) from the closest heme.To determine the identity of the ~90° CSNO moiety in the purported S-nitrosohemoglobin, we have explored all four types of SNO species (RSNO, RS-N·-OH, RS-NH-O·, and RS-NH-OH) that could be candidates for the observed SNO species, using simple models (R = Me) that can be computed at a high level. By comparison of the calculated structures to the experimental crystallographic data, we have discovered that the thionitroxide radical (Cys-S-NH-O·) is consistent with the observed SNO structures in both β1 and β2 subunits.Correspondence to: K. N. Houk. Supporting Information Available: Complete reference 9, the NO-modified hemoglobin, and the detailed structures and energetics of stationary points on potential energy surfaces of the four SNO species. These materials are available free of charge via the Internet at http://pubs.acs.org. NIH Public AccessAuthor Manuscript J Am Chem Soc...

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Narrow molecular weight resins by a free-radical polymerization process

Cited by 2,021 publications

References 0 publications

"Living" radical polymerization. 1. Possibilities and limitations

"Living" radical polymerization. 1. Possibilities and limitations

Jacketed polymers: Controlled synthesis of mesogen‐jacketed polymers and block copolymers

Thionitroxides, RSNHO^•: The Structure of the SNO Moiety in “S-Nitrosohemoglobin”, A Possible NO Reservoir and Transporter

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Narrow molecular weight resins by a free-radical polymerization process

Cited by 2,021 publications

References 0 publications

"Living" radical polymerization. 1. Possibilities and limitations

"Living" radical polymerization. 1. Possibilities and limitations

Jacketed polymers: Controlled synthesis of mesogen‐jacketed polymers and block copolymers

Thionitroxides, RSNHO•: The Structure of the SNO Moiety in “S-Nitrosohemoglobin”, A Possible NO Reservoir and Transporter

Contact Info

Product

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Thionitroxides, RSNHO^•: The Structure of the SNO Moiety in “S-Nitrosohemoglobin”, A Possible NO Reservoir and Transporter