The kinetics and mechanism of N-carboxy-α-amino-acid anhydride (NCA) polymerisation to poly-amino acids

Szwarc, M.

doi:10.1007/bfb0050964

Cited by 124 publications

(9 citation statements)

References 86 publications

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“…Besides the biodegradability/biocompatibility of polyesters/polyethers and the many biomedical applications, the major impact of polymer chemists, in their effort to mimic Nature, is the synthesis of polypeptides. Usually the polymerization is carried out via the ring opening of α-amino acid N -carboxyanhydrides (NCAs) using mainly primary amines as initiators, under inert or high-vacuum conditions. − The intensive interest in peptide-based polymers steams from their ability to bear several functionalities and to form high order structures, mimicking the Natural relative proteins . Since the synthesis of linear polypeptides is reported by comprehensive reviews and books, − in this Perspective we will only focus on the synthesis of polypeptides via ROP of NCAs with complex macromolecular architectures.…”

Section: Star Polymersmentioning

confidence: 99%

50th Anniversary Perspective: Polymers with Complex Architectures

et al. 2017

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The scope of this Perspective is to highlight innovative contributions in the synthesis of well-defined complex macromolecular architectures and to emphasize the importance of these materials to polymer physical chemistry, physics, theory, and applications. In addition, this Perspective tries to enlighten the past and show possible pathways for the future. Among the plethora of polymerization methods, we briefly report the impact of the truly living and controlled/ living polymerization techniques focusing mainly on anionic polymerization, the mother of all living and controlled/living polymerizations. Through anionic polymerization well-defined model polymers with complex macromolecular architectures having the highest molecular weight, structural and compositional homogeneity can be achieved. The synthesized structures include star, comb/graft, cyclic, branched and hyberbranched, dendritic, and multiblock multicomponent polymers. In our opinion, in addition to the work needed on the synthesis, properties, and application of copolymers with more than three chemically different blocks and complex architecture, the polymer chemists in the future should follow closer the approaches Nature, the perfect chemist, uses to make functional complex macromolecular structures by noncovalent chemistry. Moreover, development of new analytical methods for the characterization/purification of polymers with complex macromolecular architectures is essential for the synthesis and properties study of this family of polymeric materials.

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Section: Star Polymersmentioning

confidence: 99%

50th Anniversary Perspective: Polymers with Complex Architectures

et al. 2017

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“…The ring opening polymerization (ROP) of cyclic monomers is still the most promising synthetic route toward PAAs. Due to the existence of multiple active sites located on NCA or in the NTA ring, including carbonyl groups at 2- and 5-positions for nucleophilic attack and acidic protons of 3-NH and 4-CH groups, various initiators have been carried out for polymerization including amines ( Kricheldorf, 1987 ), trimethylsilyl (TMS) containing compounds, ( Lu and Cheng, 2007 , 2008 ; Yuan et al, 2016 ; Baumgartner et al, 2017 ; Yuan et al, 2018 ), salts ( Szwarc, 1965 ; Wu et al, 2018 ), (activated) alcohols ( Zhao et al, 2019 ; 2020 ), N -heterocyclic carbene ( Guo and Zhang, 2009 ; Falivene et al, 2016 ; Falivene and Cavallo, 2017 ), transition metal catalysts ( Deming, 1997 ), rare earth complexes ( Ling et al, 2012 ; Peng et al, 2012 ; Tao et al, 2014 ), and so on.…”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory Studies on the Synthesis of Poly(α-Amino Acid)s Via the Amine-Mediated Ring Opening Polymerizations of N-Carboxyanhydrides and N-Thiocarboxyanhydrides

2021

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To synthesize well-defined poly (α-amino acid)s (PAAs), ring opening polymerizations (ROP) of cyclic monomers of α-amino acid N-carboxyanhydrides (NCAs) and N-thiocarboxyanhydrides (NTAs) are most widely used. In this mini-review, we summarize the mechanism details of the monomer preparation and ROP. The present study used density functional theory calculations to reveal the mechanisms together with experimental phenomena in the past decades. Detailed discussion includes normal amine mechanism and the selectivity of the initiators bearing various nucleophilic groups.

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“…Rate of initiation with the primary amine group is usually fast, and therefore, all the polymer chains start to grow simultaneously. On the contrary, initiation of ROP of NCA by the hydroxyl group proceeds significantly slower than the chain propagation, leading to uncontrolled polymerization and, consequently, to poorly defined products . This is in contrast to ROP of several other heterocyclic monomers, like epoxides, lactones/lactides, and cyclic carbonates, where the alkoxide/hydroxyl end-groups are the active species.…”

mentioning

confidence: 99%

Ring-Opening Polymerization of N-Carboxyanhydrides Initiated by a Hydroxyl Group

2017

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We report on a method for preparation of welldefined synthetic polypeptides by ring-opening polymerization (ROP) of α-amino acid N-carboxyanhydrides (NCA) initiated by a hydroxyl group. To overcome the issue of slow initiation by hydroxyl group, an acid catalyst was used in the initiation step to catalyze opening of the NCA ring by the hydroxyl group and to simultaneously suppress further chain propagation by protonation of the formed amine group. In this way, we have separated slow initiation from the fast chain propagation, since such a combination leads to poorly defined products, and instead performed them in a successive manner. Only after completion of the initiation, the propagation was started by the addition of a base to deprotonate the ammonium group. This method was successfully applied for the synthesis of homopolypeptides by using alcohol as an initiator as well as polypeptide-based block copolymers by using poly(ethylene glycol) or poly(styrene) macroinitiator terminated with the hydroxyl group. This approach not only expands the pool of possible initiators, but also significantly facilities the preparation of polypeptide-based hybrid polymers.

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The kinetics and mechanism of N-carboxy-α-amino-acid anhydride (NCA) polymerisation to poly-amino acids

Cited by 124 publications

References 86 publications

50th Anniversary Perspective: Polymers with Complex Architectures

50th Anniversary Perspective: Polymers with Complex Architectures

Density Functional Theory Studies on the Synthesis of Poly(α-Amino Acid)s Via the Amine-Mediated Ring Opening Polymerizations of N-Carboxyanhydrides and N-Thiocarboxyanhydrides

Ring-Opening Polymerization of N-Carboxyanhydrides Initiated by a Hydroxyl Group

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