Inclusion of isolated α-amino acids along the polylactide chain through organocatalytic ring-opening copolymerization

Kivijärvi, Tove; Pappalardo, Daniela; Olsén, Peter; Finne‐Wistrand, Anna

doi:10.1016/j.eurpolymj.2020.109703

Cited by 12 publications

(10 citation statements)

References 60 publications

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“…Indeed, Finne-Wistrand et al have demonstrated that 3,6-(dimethyl)morpholine-2,5-dione, whose structure is identical to LA with the exception of the amide bond, has less ring-strain than LA thus leading to the preferential homopropagation of LA. 51 The 1 H and 13 C NMR spectra of the precipitated copolymers contain all the peaks corresponding to both PLA and PMD repeating units as well as aromatic protons characteristic of the benzyl groups on the copolymer chainends (see Figure S6). Comparing the area of the CH 3 proton peak of the PLA units to the CH 2 and CH protons peak of the PMD units, the composition of each copolymer was determined.…”

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confidence: 99%

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Simple and Rapid Mechanochemical Synthesis of Lactide and 3S-(Isobutyl)morpholine-2,5-dione-Based Random Copolymers Using DBU and Thiourea

et al. 2021

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There is a growing interest surrounding morpholine-2,5-dionebased materials due to their impressive biocompatibility as well as their capacity to break down by hydrolytic and enzymatic pathways. In this study, the ringopening (co)polymerization of leucine-derived 3S-(isobutyl)morpholine-2,5dione (MD) and lactide (LA) was performed via ball-milling using a catalytic system composed of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 3-[3,5bis(trifluoromethyl)phenyl]-1-cyclohexylthiourea (TU). Once the homopolymerizations of MD and LA optimized and numerous parameters were studied, the mechanochemical ring-opening copolymerization of these monomers was explored. The feasibility of ring-opening copolymerizations in mechanochemical systems was demonstrated and a range of P(MD-co-LA) copolymers were produced with varying proportions of MD (23%, 48%, and 69%). Furthermore, the beneficial cocatalytic effects of TU with regards to ROP control were found to be operative within mechanochemical systems. Further parallels were observed between solution-and mechanochemical-based ROPs.

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“…Furthermore, differences in ring-strain may equally contribute to these differences in reactivity. Indeed, Finne-Wistrand et al have demonstrated that 3,6-(dimethyl)morpholine-2,5-dione, whose structure is identical to LA with the exception of the amide bond, has less ring-strain than LA thus leading to the preferential homopropagation of LA …”

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confidence: 99%

Simple and Rapid Mechanochemical Synthesis of Lactide and 3S-(Isobutyl)morpholine-2,5-dione-Based Random Copolymers Using DBU and Thiourea

et al. 2021

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“…ROPs are thermodynamically driven processes, and the equilibrium between growth and depolymerization typically changes with temperature; as previously mentioned, a polymerization temperature well below T c , or a high T c , is generally beneficial to increase monomer conversion. Polar solvents can be detrimental, because they may significantly decrease the T c of a ROP process; this is the likely cause of the failure of TBD-catalyzed lactide ROP at 30 °C [copolymerization of L-LA with dimethylmorpholinedione, <10% conversion of both monomers after 4 days, and 1 M total initial monomer concentration], when conducted in polar NMP . In order to demonstrate this point, we have conducted the DL-LA polymerization in NMP at different temperatures (Figure A) and variable monomer concentrations (see Supporting Information, Figure S2), clearly showing that monomer conversion increases at lower temperatures; of note, the increase in NMP viscosity and the decrease in initiator solubility also cast a lower limit to the polymerization temperature, which here we have limited to 5 °C.…”

Section: Resultsmentioning

confidence: 99%

Versatile Preparation of Branched Polylactides by Low-Temperature, Organocatalytic Ring-Opening Polymerization in N-Methylpyrrolidone and Their Surface Degradation Behavior

et al. 2021

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We describe how the organocatalytic, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-based lactide ring-opening polymerization can be effectively performed in a very polar solvent, N-methylpyrrolidone (NMP). Due to a low ceiling temperature, this "living" mechanism has been unreported to date, but we here demonstrate that through a combination of low temperature and repeated monomer additions (starve-fed process), this mechanism enables the generation of a plethora of multifunctional homo-and (stereo)block-poly(lactide)s (PLAs) with exquisite control of the molecular weight dispersity (typically Đ < 1.1) and topology (from linear through 4-, 6-, or 8-armed stars and up to ∼140 armed combs). They are scarcely obtainable or inaccessible through more classical synthetic methods due to the poor solubility of multifunctional initiators (polyols) in most organic solvents and monomer melts. In these precisely designed structures, branching significantly altered the nature of the materials' hydrolytic degradation, allowing them to acquire a pronounced surface character (as opposed to the bulk degradation of linear polymers). Finally, we have assessed the amenability of this method to in situ block copolymerization by using the tacticity of PLLA blocks in PLLA-b-PDLLA versus PDLLA-b-PLLA (L-LA polymerized before or after DL-LA) as a sensitive method to detect (stereochemical) defects.

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“…First, ester-linked alpha hydroxy acid homodimers and amide-linked alpha hydroxy acid-alpha amino acid heterodimers can cyclize into 6-membered rings, which can then participate in ring-opening polymerization (ROP). ROP is a common methodology for chain growth polymerization via the use of heterocyclic monomers, which have greater reactivity than their corresponding linear forms [64][65][66][67]. In the context of depsipeptide formation, ROP of dilactone rings (alpha hydroxy acid cyclic dimers) and morpholinediones (alpha amino acid-alpha hydroxy acid heterodimers) is expected to increase the susceptibility to nucleophilic attack of the ester-carbonyl to ester-amide exchange and ester-ester exchange [68].…”

Section: Discussionmentioning

confidence: 99%

Differential Oligomerization of Alpha versus Beta Amino Acids and Hydroxy Acids in Abiotic Proto-Peptide Synthesis Reactions

Frenkel-Pinter

Jacobson

Eskew-Martin

et al. 2022

Life

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The origin of biopolymers is a central question in origins of life research. In extant life, proteins are coded linear polymers made of a fixed set of twenty alpha-L-amino acids. It is likely that the prebiotic forerunners of proteins, or protopeptides, were more heterogenous polymers with a greater diversity of building blocks and linkage stereochemistry. To investigate a possible chemical selection for alpha versus beta amino acids in abiotic polymerization reactions, we subjected mixtures of alpha and beta hydroxy and amino acids to single-step dry-down or wet-dry cycling conditions. The resulting model protopeptide mixtures were analyzed by a variety of analytical techniques, including mass spectrometry and NMR spectroscopy. We observed that amino acids typically exhibited a higher extent of polymerization in reactions that also contained alpha hydroxy acids over beta hydroxy acids, whereas the extent of polymerization by beta amino acids was higher compared to their alpha amino acid analogs. Our results suggest that a variety of heterogenous protopeptide backbones existed during the prebiotic epoch, and that selection towards alpha backbones occurred later as a result of polymer evolution.

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Inclusion of isolated α-amino acids along the polylactide chain through organocatalytic ring-opening copolymerization

Cited by 12 publications

References 60 publications

Simple and Rapid Mechanochemical Synthesis of Lactide and 3S-(Isobutyl)morpholine-2,5-dione-Based Random Copolymers Using DBU and Thiourea

Simple and Rapid Mechanochemical Synthesis of Lactide and 3S-(Isobutyl)morpholine-2,5-dione-Based Random Copolymers Using DBU and Thiourea

Versatile Preparation of Branched Polylactides by Low-Temperature, Organocatalytic Ring-Opening Polymerization in N-Methylpyrrolidone and Their Surface Degradation Behavior

Differential Oligomerization of Alpha versus Beta Amino Acids and Hydroxy Acids in Abiotic Proto-Peptide Synthesis Reactions

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