How controlled and versatile is N-carboxy anhydride (NCA) polymerization at 0 °C? Effect of temperature on homo-, block- and graft (co)polymerization

Habraken, Gjm Gijs; Peeters, Marloes; Dietz, Chjt Carin; Koning, CE Cor; Heise, Andreas

doi:10.1039/b9py00337a

Cited by 145 publications

(182 citation statements)

References 37 publications

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“…A likely explanation for the polymerization control observed under high vacuum is that CO 2 acts to promote side reactions of growing chains with monomer, polymer, or solvent, and its removal from the reaction medium under vacuum inhibits these reactions, and promotes controlled polymerization. A number of early and recent studies support this role of CO 2 as being detrimental to amine initiated NCA polymerizations, where for some NCAs it is able to decrease chain propagation rate by reversibly forming a carbamate with the amine end-group and may also catalyze side-reactions [41,42]. Thus, it is reasonable to speculate (vide infra) that removal of CO 2 from NCA polymerizations under high vacuum is the dominant factor in enabling controlled chain growth in these systems.…”

Section: Insert Equation 11mentioning

confidence: 99%

Synthesis and Self-Assembly of Well-Defined Block Copolypeptides via Controlled NCA Polymerization

Deming

2013

Hierarchical Macromolecular Structures: 60 Years After the Staudinger Nobel Prize II

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Section: Insert Equation 11mentioning

confidence: 99%

Synthesis and Self-Assembly of Well-Defined Block Copolypeptides via Controlled NCA Polymerization

Deming

2013

Hierarchical Macromolecular Structures: 60 Years After the Staudinger Nobel Prize II

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“…Furthermore, unwanted side reactions have also been shown to effectively be diminished by simply running the polymerization at 0 C instead of room temperature, or at reduced pressures. [55][56][57] Assemblies with Polypeptide Coronas The past two decades have seen several literature reports of aqueous assembly of block copolymers with peptide corona chains, whereby responsiveness is governed in part by changes in the secondary structure. 11,42,[58][59][60][61][62][63][64][65][66][67][68][69][70][71][72] Much of this research focus has been devoted to pH-responsive block copolymers containing peptides such as poly(L-lysine) (PLys) (pKa 10.3) 73 and poly(L-glutamic acid) (PLGA) (pKa 4.3) 70 which exhibit helix-coil transitions associated with the charged state of the amino or carboxylic acid side chains of PLys and PGlu respectively.…”

Section: Assembly and Responsiveness Of Peptide-based Diblock Copolymersmentioning

confidence: 99%

Self‐assembly and responsiveness of polypeptide‐based block copolymers: How “Smart” behavior and topological complexity yield unique assembly in aqueous media

Ray¹,

Johnson²,

Savin³

2013

J Polym Sci B Polym Phys

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Polypeptide-based amphiphilic block copolymers are an attractive class of materials given their ability to form welldefined aqueous nanoassemblies that respond to external stimulus through secondary structure transitions. This report will highlight recent literature in the area of polypeptide-based block copolymer self-assembly, with the major focus being on how the responsive nature and structural complexity of the polypeptide blocks can be incorporated into systems with complex topologies such as ABA/BAB/ABC triblock copolymers, AB 2 and A 2 B star copolymers, and miktoarm l-ABC star terpolymers. In particular, the role of interfacial curvature changes and how they result in morphology transitions will be discussed. The 'smart' assembly properties of peptides in complex block copolymer topologies can lead to enhanced responsiveness, morphological complexity, and unique morphological transitions with varying solution conditions. V C 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 508-523 KEYWORDS: amphiphiles; biomimetic; block copolymers; selfassembly INTRODUCTION Amphiphilic block copolymers are able to self-assemble into well-defined nanostructures in aqueous solution. [1][2][3][4][5] The equilibrium morphology and aggregation number of diblock copolymer assemblies is primarily determined by the balance of three energetic factors: (1) interfacial tension, (2) corona chain crowding, and (3) core chain stretching. The balance of these three factors dictates an equilibrium curvature for the aggregate. 6-8 Typically, solution morphologies formed by amphiphilic block copolymers follow a trend of increasing interfacial curvature. As the hydrophilic fraction is increased in the copolymer, vesicles, cylindrical micelles, and spherical micelles (in the order of increasing interfacial curvature,) are the most common morphologies (Figure 1). 5,9,10 Physically, this is explained as a balance between entropic freedom of the hydrophilic coronal chains and shielding of the hydrophobic blocks from the aqueous solution; as the hydrophilic fraction increases, the chains are more able to effectively stabilize these assemblies without close-packing, and the free energy of the system is lowered when the coronal chains are provided more entropic freedom/mobility through increased curvature.

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“…The reactions were performed at 0 °C as it was shown previously that this lower temperature avoids side reactions at the chain ends, which commonly lead to in-ring structures and chain-end termination, as well as "in-main-chain" reactions [41,42]. After isolation of the polymers the benzyl protecting groups of the Glu and Lys side chains were removed by dissolution in TFA and by reaction with 33% HBr in acetic acid (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

Random Poly(Amino Acid)s Synthesized by Ring Opening Polymerization as Additives in the Biomimetic Mineralization of CaCO3

Dmitrović

Habraken²,

Hendrix

et al. 2012

Polymers

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Biominerals such as bones, teeth and seashells, very often have advanced material properties and are a source of inspiration for material chemists. As in biological systems acidic proteins play an important role in regulating the formation of CaCO 3 biominerals, we employ poly(amino acid)s to mimic the processes involved in the laboratory. Here we report on the synthesis of random aminoacid copolymers of glutamic acid (Glu), lysine (Lys) and alanine (Ala) using the ring opening polymerization (ROP) of their respective N-carboxy anhydrides (NCA). The synthetic approach yields a series of polymers with different monomer composition but with similar degrees of polymerization (DP 45-56) and comparable polydispersities (PDI 1.2-1.6). Using random copolymers we can investigate the influence of composition on the activity of the polymers without having OPEN ACCESSPolymers 2012, 4 1196 to take into account the effects of secondary structure or specific sequences. We show that variation of the Glu content of the polymer chains affects the nucleation and thereby also the particle size. Moreover, it is shown that the polymers with the highest Glu content affect the kinetics of mineral formation such that the first precipitate is more soluble than in the case of the control.

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How controlled and versatile is N-carboxy anhydride (NCA) polymerization at 0 °C? Effect of temperature on homo-, block- and graft (co)polymerization

Abstract: The polymerization of N-carboxyanhydride (NCA) at low temperatures is controlled and allows the synthesis of a variety of well-defined polypetides.

Cited by 145 publications

References 37 publications

Synthesis and Self-Assembly of Well-Defined Block Copolypeptides via Controlled NCA Polymerization

Synthesis and Self-Assembly of Well-Defined Block Copolypeptides via Controlled NCA Polymerization

Self‐assembly and responsiveness of polypeptide‐based block copolymers: How “Smart” behavior and topological complexity yield unique assembly in aqueous media

Random Poly(Amino Acid)s Synthesized by Ring Opening Polymerization as Additives in the Biomimetic Mineralization of CaCO3

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