Binary organocatalytic system for ring-opening polymerization of ε-caprolactone and δ-valerolactone: Synergetic effects for enhanced selectivity

Li, Yunxin; Zhao, Na; Wei, Chuanzhi; Sun, Abin; Liu, Shaofeng; Li, Zhibo

doi:10.1016/j.eurpolymj.2018.12.012

Cited by 26 publications

(14 citation statements)

References 51 publications

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“…The synthesis of aliphatic polyesters, e.g. polycaprolactone (PCL) and poly(lactic acid) (PLA), is a topic of wide interest in both academic and industrial research owing to their important applications in agriculture, packaging, and biomedical fields. , In comparison to condensation polymerization, the ring-opening polymerization (ROP) of cyclic esters is a convenient methodology for the synthesis of well-defined polyesters with a catalyst and/or an initiator, including metal-based catalysts, − enzymes, organocatalysts, − and dual catalysts. − In particular, this method could produce polyester with high molecular weights, i.e. ultrahigh-molecular-weight PCL (UHMWPCL, M n > 50 kg mol –1 ), which is quite desirable as a potential scaffold material for tissue engineering …”

Section: Introductionmentioning

confidence: 99%

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Aluminum Complexes Bearing Bidentate Amido–Phosphine Ligands for Ring-Opening Polymerization of ε-Caprolactone: Steric Effect on Coordination Chemistry and Reactivity

et al. 2019

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The aluminum complexes LAlMe2 (Al1–Al5: LH = 2,6-(R1)2-4-R2-C6H2NHCH2C6H4-2-PPh2; Al1, R1 = H, R2 = H; Al2, R1 = Me, R2 = H; Al3, R1 = i Pr, R2 = H; Al4, R1 = Ph2CH, R2 = i Pr; Al5, R1 = Cl, R2 = H) have been synthesized and characterized by elemental analysis and 1H, 13C, and 31P NMR. NMR analysis in solution reveals an interesting hemilabile coordination of the soft P donor. The molecular structures of Al2–Al4 were defined by X-ray diffraction studies, showing a distorted-tetrahedral geometry around the aluminum center in all structures. Careful comparison of these crystal structures suggested that different substituents on the ligands could lead to unignorable changed coordination environments around the Al center, thus affecting their catalytic properties. In the presence of BnOH, complexes Al1–Al5 efficiently catalyzed the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) with high conversions in a controlled manner, and high molecular weights (M n up to 118.6 kg mol–1) of polycaprolactones (PCLs) were readily prepared. Immortal polymerizations by Al4 having bulky Ph2CH groups were also studied with up to 20 equiv of alcohols and 2000 equiv of monomers, without sacrificing polymerization control.

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Section: Introductionmentioning

confidence: 99%

“…

have been synthesized and characterized by elemental analysis and 1 H, 13 C, and 31 P NMR. NMR analysis in solution reveals an interesting hemilabile coordination of the soft P donor.

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confidence: 99%

Aluminum Complexes Bearing Bidentate Amido–Phosphine Ligands for Ring-Opening Polymerization of ε-Caprolactone: Steric Effect on Coordination Chemistry and Reactivity

et al. 2019

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“…The MALDI mass spectrometry characterization of PCLs was mostly performed using DHB as a matrix [ 32 , 35 , 40 , 60 , 61 , 62 , 63 ], but other matrices were also employed: dithranol [ 33 , 50 , 64 ], 2-(4-hydroxyphenylazo)-benzoic acid [ 57 ], and CHCA [ 39 ]. For CD derivatives, CHCA [ 25 , 45 , 46 , 65 , 66 , 67 , 68 , 69 ] and DHB [ 70 , 71 , 72 ] were the most employed matrices; therefore, we compared the M n evolution using these two matrices for MALDI MS analysis ( Figure 6 ).…”

Section: Resultsmentioning

confidence: 99%

“…PCLs have been prepared previously with very good results using alcohol initiators and various organocatalysts, such as acids [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ] and binary systems comprised of thioureas with different bases [ 36 , 37 , 38 , 39 ] or with trifluoroacetic acid [ 40 ], as well as mixtures of DMAP and its protonated form with trifluoromethanesulfonic acid [ 41 ]. In general, acid organocatalysts are more active for the ring-opening of ε-CL, but when dealing with CDs as initiators, the organocatalysts have to be carefully chosen, as CDs may undergo hydrolysis in acidic media—which increases with temperature and concentration [ 2 ]; however, in basic media, CD molecules are stable.…”

Section: Introductionmentioning

confidence: 99%

Cyclodextrin-Oligocaprolactone Derivatives—Synthesis and Advanced Structural Characterization by MALDI Mass Spectrometry

Peptu¹,

Blaj²,

Balan-Porcăraşu³

et al. 2022

Polymers

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Cyclodextrins have previously been proven to be active in the catalysis of cyclic ester ring-opening reactions, hypothetically in a similar way to lipase-catalyzed reactions. However, the way they act remains unclear. Here, we focus on β-cyclodextrin’s involvement in the synthesis and characterization of β-cyclodextrin-oligocaprolactone (CDCL) products obtained via the organo-catalyzed ring-opening of ε-caprolactone. Previously, bulk or supercritical carbon dioxide polymerizations has led to inhomogeneous products. Our approach consists of solution polymerization (dimethyl sulfoxide and dimethylformamide) to obtain homogeneous CDCL derivatives with four monomer units on average. Oligomerization kinetics, performed by a matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) optimized method in tandem with 1H NMR, revealed that monomer conversion occurs in two stages: first, the monomer is rapidly attached to the secondary OH groups of β-cyclodextrin and, secondly, the monomer conversion is slower with attachment to the primary OH groups. MALDI MS was further employed for the measurement of the ring-opening kinetics to establish the influence of the solvents as well as the effect of organocatalysts (4-dimethylaminopyridine and (–)-sparteine). Additionally, the mass spectrometry structural evaluation was further enhanced by fragmentation studies which confirmed the attachment of oligoesters to the cyclodextrin and the cleavage of dimethylformamide amide bonds during the ring-opening process.

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“…The proximity of the energy gap between the highest occupied molecular orbital (HOMO) of the monomer and the LUMO of the initiator complex increases the electron transfer probability, and this leads to a rise in the polarization of the carbonyl in the monomer, thus increasing the tendency of metal-oxygen bond formation. 29 The synthesis of PVL, which has been studied less compared to polylactide and caprolactone, has been achieved by organocatalytic systems, 30,31 metal salts, 27,32,33 tin carboxylates, 34 diphenyl phosphate 35 and enzymes. 36 However, there are no theoretical and experimental studies reported so far that investigate the effect of the initiator metal on the coordination-insertion mechanism of PVL.…”

Section: Introductionmentioning

confidence: 99%

Investigation of initiator metal efficiency in the ring‐opening polymerization of lactones: an experimental and computational study

Gümüştaş

Balcan

Kınal

2022

Polymer International

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Poly(δ‐valerolactone) (PVL) was synthesized by ring‐opening polymerization (ROP), employing tin(II) acetate (SnAcet2), lead(II) acetate trihydrate (PbAcet2·3H2O) and cadmium(II) acetate dihydrate (CdAcet2·2H2O) complexes as initiators without any co‐initiator. The highest molecular weight PVL (45 438 g mol−1, 91% yield) was obtained with CdAcet2·2H2O. Characterization of the synthesized products was performed by FTIR, 1H NMR, 13C NMR, gel permeation chromatography (GPC), matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐TOF/TOF MS), TGA and DSC. Electrostatic data (natural bond orbital and Hirshfeld) and lowest unoccupied molecular orbital (LUMO) of the initiators were obtained by using several density functional theory methods (B3LYP, ωB97X‐D, PBEPBE, BPV86, HSEH1PBE, MPW1PW91, M06 and M062X). In addition, the initiation stage of the ROP mechanism of δ‐valerolactone with these metal acetate complexes was investigated at the ωB97X‐D level with a mixed basis set. It was computationally determined that the most effective initiator was also CdAcet2. The molecular weight variation of PVLs synthesized with these initiators can be associated with the combined evaluation of atomic charge, LUMO and orbital overlap analyses. The computationally obtained reaction barriers for the initiators support this idea, also. In addition, toxicity tests carried out for PVLs synthesized with acetate complexes containing Sn, Cd and Pb revealed that the Sn and Cd complexes do not have a toxic effect on cell viability at some dilution rates. © 2021 Society of Industrial Chemistry.

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Binary organocatalytic system for ring-opening polymerization of ε-caprolactone and δ-valerolactone: Synergetic effects for enhanced selectivity

Cited by 26 publications

References 51 publications

Aluminum Complexes Bearing Bidentate Amido–Phosphine Ligands for Ring-Opening Polymerization of ε-Caprolactone: Steric Effect on Coordination Chemistry and Reactivity

Aluminum Complexes Bearing Bidentate Amido–Phosphine Ligands for Ring-Opening Polymerization of ε-Caprolactone: Steric Effect on Coordination Chemistry and Reactivity

Cyclodextrin-Oligocaprolactone Derivatives—Synthesis and Advanced Structural Characterization by MALDI Mass Spectrometry

Investigation of initiator metal efficiency in the ring‐opening polymerization of lactones: an experimental and computational study

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