Ring-opening Polymerization Of Lactones Research Articles

Rare earth metal initiated ring-opening polymerization of lactones

The progress in the synthesis of organolanthanide complexes supports the exploration of these compounds as initiators for ring-opening polymerization (ROP) of lactones. The performance of these initiators in terms of yield, molecular weight, polydispersity, stereoregularity is affected by the ligands and by the oxidation state of the respective rare earth metals. Several initiators are known to initiate living polymerization of lactones with excellent polydispersities of the thus obtained polymers. Differences in the performance of the initiators are caused by differences in the initiation mechanism, chain growth mechanism, or side reactions. ROP of lactones was extended to block- and graft copolymerization with polylactones, polylactides, and polyolefins either by simply utilizing living polymer chain ends, by transformation of living polymer chain ends, or by usage of polyinitiators.

A Catalytic Approach for Cationic Living Polymerization: Sc(OTf)3-Catalyzed Ring-Opening Polymerization of Lactones

A Catalytic Approach for Cationic Living Polymerization: Sc(OTf)₃-Catalyzed Ring-Opening Polymerization of Lactones

Complexes of Group 3 Metals and Lanthanides That Contain Siloxane-Bridged Bisaminopyridinato Ligands: Synthesis, Structure, and Application in the Ring-Opening Polymerization of Lactones

The reaction of one equivalent of dilithiated O(SiMe2-Ap-H)(2) [Ap-H = -N(2-amino-4-methylpyridine)] (1), generated in situ, with LnCl(3) (Ln = Y, Sm) in THF affords O(SiMe2-Ap)(2)YCl(THF)(2) (2) or O(SiMe2-Ap)(2)SmCl(THF)(3) (3). In contrast, the reaction of one or two equivalents of dilithiated 1, again generated in situ, with LaBr3 in THF affords O(SiMe2-Ap)(2))(2)LaLi(THF)(3) (4). An X-ray structural analysis of 2 and 3 reveal the O(SiMe2-Ap)(2-) ligand to bind in a planar tetradentate manner. Equivalent Sm-N distances in 3 indicate a delocalized binding mode. Compound 2 reacts with Bu4NBH4, NaBH4 or LiCH(SiMe3)(2) to give the corresponding ate complexes O(SiMe2-Ap)(2)Y(BH4)Cl(THF) Bu4N (5), O(SiMe2-Ap)(2)Y(BH4)(2)Na(THF)(2) (6) and O(SiMe2-Ap)(2)Y(CH(TMS)(2))(2)Li(THF)(3) (7), respectively. The steric demand of the O(SiMe2-Ap)(2-) ligand is not large enough to stabilize monoalkyl or monoborohydride complexes. Complex 4 has been used as an initiator for the ring-opening polymerization of epsilon-caprolactone or delta-valerolactone. In both cases an almost linear relation between the monomer-to-initiator ratio and the molecular weight of the obtained polyester is observed. By conducting the polymerization in neat epsilon-caprolactone at room temperature a solid polyester block is formed after 3 min (300000 g.mol(-1), M-w/M-n 2.3).

Polymerization of lactides and lactones. II. Ring-opening polymerization of ?-caprolactone andDL-lactide by organoacid rare earth compounds

Ring-opening polymerization of lactone and lactide have been initiated with rare earth organoacid compounds, such as lanthanum acetate in bulk. The polymerization mechanism is in agreement with the “nonionic–coordination–insertion” mechanism, which involves the selective cleavage of the acyl–oxygen bond of the monomer. These organoacid rare earth initiators can give high yield of medium to high molecular weight products. An interesting aspect of this investigation is the good agreement between the performance of the initiator and the solubility of the initiator in the monomer. However, the relatively slow initiation step makes it difficult to control the molecular weight and results in a broad molecular weight distributions. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1941–1948, 1999

Reactions of ε-Caprolactone with (Alkyne)zirconocene Complexes: Investigation of Elemental Steps in Catalytic Ring-Opening Polymerization of Lactones

The reactions of Cp2Zr(L)(η2-Me3SiC2SiMe3) (L = THF, pyridine) with ϵ-caprolactone, cyclohexanone and cycloheptanone result in an insertion of the carbonyl group into the zirconacyclopropene ring system of the alkyne complexes to yield the five-membered metallacyclic spiro-zirconadihydrofurane complexes 1, 3, 4. The product with ϵ-caprolactone is not stable at room temperature and was identified only by NMR spectra and chemical reactions. Starting from rac-(ebthi)Zr(η2-Me3SiC2SiMe3) with ϵ-caprolactone and ethylene carbonate under analogous conditions more stable complexes (2, 5) were obtained. Complexes 2 and 3 were characterized by X-ray crystal-structure analysis. Complexes 1 and 2 react with further ϵ-caprolactone in a catalytic ring-opening polymerization. The polymerization reactions were monitored by NMR spectroscopy.

Ethyl Glucoside as a Multifunctional Initiator for Enzyme-Catalyzed Regioselective Lactone Ring-Opening Polymerization

The one-pot biocatalytic synthesis of novel amphiphilic products consisting of an ethyl glucopyranoside (EGP) headgroup and a hydrophobic chain is described. The porcine pancreatic lipase (PPL) catalyzed ring-opening polymerization of e-caprolactone (e-CL) by the multifunctional initiator EGP was carried out at 70 °C in bulk. Products of variable oligo(e-CL) chain length (Mn = 450, 2200) were formed by variation of the e-CL/EGP ratio. Extension of this approach using Candida antarctica lipase (Novozym-435) and EGP as the initiator for trimethylene carbonate (TMC) ring-opening polymerization also resulted in the formation of an EGP−oligo(TMC) conjugate (Mn = 7200). Structural analysis by 1H, 13C, and COSY (13C-13C) NMR experiments showed that the reaction was highly regiospecific; i.e., the oligo(e-CL)/oligo(TMC) chains formed were attached by an ester/carbonate link exclusively to the primary hydroxyl moiety of EGP.

Enzyme-catalyzed polymerization: an opportunity for innovation

—The application of enzymes in organic synthesis has attracted the attention of many research workers in recent years. Specific enzymatic catalysis is expected to synthesize polymers with high selectivity and/or novel structures. Up to now, the enzymatic synthesis of polyphenols, cellulose, lignin, and polypeptides, as well as non-natural polymers, has been successfully achieved. This review discusses the systematic synthesis of polyphenols using horseradish peroxidase-hydrogen peroxide (HRP-H2O2), the ring-opening polymerization of lactones using the enzyme lipase, and the successful synthesis of cellulose using the enzyme cellulase. The polyphenols enzymatically synthesized have been explored as substitutes of phenol-formaldehyde resins to eliminate the pollution caused by formaldehyde in the environment. Due to their unique π-conjugation nature, these polymers have potential applications in nonlinear optics and in the fabrication of light-emitting diodes. The enzymatic polymerizations using lipase have been expanded to ring-opening polymerization and copolymerization of medium-sized lactones yielding polyesters. It is predicted that enzymatic polymerization will revolutionize the polymer and plastics industries in the 21st century for the synthesis of novel polymers with specific properties.

Extremely Efficient Catalysis of Immobilized Lipase in Ring-opening Polymerization of Lactones

Abstract An immobilized lipase derived from Candida antarctica was used as catalyst for the ring opening polymerization of lactones. A small amount of the immobilized enzyme showed the extremely efficient catalysis in the lactone polymerization. The polymerization in the presence of 1-octanol enhanced the rate of reaction.

End-functionalized poly(ϵ-caprolactone) oligomers through heterogeneous catalysis in protic conditions: a mechanistic approach

An heterogeneous system constituted of aluminium alkoxides grafted on a porous silica has been used for the ring opening polymerization of lactones. Adding alcohol in excess induces a rapid exchange reaction between the grafted active centres and these free alcohol molecules present in the medium, which competes with the propagation step. The polymer chains are functionalized by end-groups issued from the alcohol and are produced in a number larger than that of metal atoms used. In addition, the active centres can be re-used for further polymerizations which brings an innovative catalytic dimension to this process. This case was engaged in the polymerization of ϵ-caprolactone and some kinetic features are reported. The activation energy is 28 kJ mol −1. The catalytic activity is strongly dependent on the alcohol concentration and exhibits some optimum. A mechanistic approach based on the share of the aluminium vacancy between the Lewis bases present in the medium was proposed to account for the experimental results. Molecular geometry calculations have been used to study the possible arrangements of the monomer-aluminium alkoxide complex.

Silylcarboxonium and Silyloxonium Ion Intermediates of the Cationic Ring-Opening Polymerization of Lactones and Tetrahydrofuran Initiated by Electrophilic Trimethylsilylating Agents

The initiation of the cationic ring-opening polymerization of lactones and tetrahydrofuran by electron-deficient organosilicon species has been investigated. The formation of the long-lived silylcarboxonium ion 1a from γ-butyrolactone and the silyloxonium ion 2a from THF has been evidenced by 1H, 13C, and 29Si NMR. The structure and NMR chemical shifts of 2a were also calculated using DFT/IGLO methods, and the results are in good agreement with experimental data. The nature of the ions is discussed in terms of the reactivity with respect to their methylated analogues. Polymerization of lactones initiated by in situ formed silylcarboxonium ions showed a much higher rate than that initiated by trimethylsilyl triflate, while polymerization of tetrahydrofuran in a similar manner failed. The mechanism of polymer initiation is discussed.

Enzyme-Catalyzed Polymerizations of ε-Caprolactone: Effects of Initiator on Product Structure, Propagation Kinetics, and Mechanism

Studies were undertaken to gain mechanistic information on lactone ring-opening polymerization reactions using porcine pancreatic lipase (PPL) as the catalyst and ε-caprolactone (ε-CL) as the monomer. Polymerizations were carried out at low water levels (0.13 mmol) and supplemented with either butanol or butylamine. Rates of monomer conversion, product molecular weight, total chain number, and chain end structure were determined by 1H NMR. In the presence of water alone, a maximum Mn of 7600 g/mol was obtained at 85% conversion, which decreased to 4200 g/mol as the reaction continued to 98% conversion. Reactions with butanol and butylamine at 100% conversion gave polymers with Mn values of 1900 and 1200 g/mol, respectively. For these three polymerizations, the total number of polymer chains increased with conversion due to a simultaneous increase in carboxylic acid chain ends. Within 4 h (∼26% monomer conversion), butylamine was completely consumed but only 37% of butanol reacted. Reactions with butylamine occurred predominantly by an enzyme-mediated route to form N-butyl-6-hydroxyhexanamide. This step was rapid relative to subsequent chain growth. In addition, the living or immortal nature of the polymerizations was assessed from plots of log{[M]0/[M]t} versus time and Mn versus conversion. These results indicate that termination and chain transfer did not occur, and we described the system as providing “controlled” polymerizations. Furthermore, an expression for the rate of propagation was derived from the experimental data which is consistent with that derived from the proposed enzyme-catalyzed polymerization mechanism. The absence of termination in conjunction with the relationship between molecular weight and the total concentration of multiple initiators suggests that ε-CL polymerization by PPL catalysis shares many features of immortal polymerizations.

One-Shot Synthesis of Polyester Macromonomer by Enzymatic Ring-Opening Polymerization of Lactone in the Presence of Vinyl Ester

Abstract Polyester macromonomers bearing a polymerizable methacryloyl or 10-undecenolyl group at the chain end were synthesized by the lipase-catalyzed ring-opening polymerization of 12-dodecanolide in the presence of a vinyl ester having the corresponding polymerizable group.

Recent Advances in Ring-Opening Polymerization of Lactones and Related Compounds

Abstract Polyesters are currently synthesized by a step-growth mechanism from a mixture of a diol and a diacid (or a diacid derivative), or from a hydroxy-acid when available. Ring-opening polymerization (ROP) of lactones and related compounds is an alternative method for the synthesis of aliphatic polyesters. Comparison of these two mechanisms is clearly in favor of the polyaddition process. The drawbacks of polycondensation are well known:high temperatures and long reaction times are required to produce high-molecular-weight chains. Even though conversion of the hydroxyl and acid group is close to completion, any departure from the reaction stoichiometry has a very detrimental effect on the chain length.

Enzymatic Ring-Opening Polymerization of Lactones to Polyesters by Lipase Catalyst: Unusually High Reactivity of Macrolides

Abstract Enzymatic ring-opening polymerization of macrolides was carried out by using various lipases as catalysts. The monomers used in this study were 11-undecanolide (12-membered, UDL) and 15-pentadecanolide (16-membered, PDL). Among the enzymes examined, lipases derived from Pseudomonas fluorescens (lipase P) and from Candida cylindracea (lipase B) gave polyUDL with high molecular weight in a high yield. From 1H and 13C NMR analysis, the polymer was found to possess the terminal structure of a carboxylic acid group at one end and a hydroxyl group at the other. The rate of the UDL polymerization using lipase P was larger than that using lipase B, whereas the polymerization of UDL using lipase B produced the polymer of higher molecular weight in comparison with that obtained by using lipase P. Lipases from Pseudomonas sp. and porcine pancreas showed a catalytic activity for the polymerization of UDL. PDL was also polymerized by lipase catalyst to give the corresponding polyester. The enzymatic polymerizations of UDL and PDL have been compared with that of 6-hexanolide (ε-caprolactone, ε-CL). The polymerization of the macrolides using lipase P proceeded much faster than that of ε-CL. This is probably due to the strong recognition of the macrolides by the lipase catalyst.

Macromolecular Engineering of Polylactones and Polylactides. 17.Cryometric and Viscosimetric Analysis of the Species Active in the Ring-Opening Polymerization of Lactones, Lactides, and Cyclic Anhydrides as Initiated by Aluminum Triisopropoxide

The effect of cyclic monomers on the coordinative structure of Al(O i Pr) 3 in benzene was investigated by cryometry. γ-Butyrolactone (γ-BL), a nonpolymerizable lactone, was first studied as a model monomer. The cryometric Job diagram for the γ-BL/Al(O i Pr) 3 system in benzene established formation of a trisolvated six-coordinate [Al(O i Pr) 3 .3γ-BL] complex. This is in operfect agreement with the hexacoordinated Al atoms as reported by 27 Al NMR. The extension of the cryometric study to a polymerizable lactone (δ-valerolactone)) confirmed that the single [Al(OiPr) 3 .3M] species is the actual initiator for the ring opening polymerization

Enzymatic Ring-Opening Polymerization of Lactones Catalyzed by Lipase

Abstract Enzymatic ring-opening polymerization of lactones was achieved by using lipase as catalyst. The polymerization of ε-caprolactone by Pseudomonas fluorescens lipase at 60 °C in bulk for 10 days afforded a polyester with average molecular weight of 7.0 × 103. From 1H and 13C NMR analysis, the polymer possesses the terminal structure of a carboxylic acid group at one end and a hydroxyl group at the other.

Grafting of polyesters onto carbon whisker surface

Acylium perchlorate groups were successfully introduced onto the surface of carbon whisker, i.e., vapor grown carbon fiber, by the reaction of surface acyl chloride groups with silver perchlorate in nitrobenzene. It was found that the cationic ring-opening polymerization of lactones, such as e-caprolactone, δ-valerolactone, and β-propiolactone, is initiated by acylium perchlorate groups introduced onto carbon whisker. During the polymerization, the corresponding polyesters were effectively grafted onto carbon whisker surface based on the propagation of polyester from the surface. The rate of polymerization increased with increasing polymerization temperature, but the percentage of grafting of polyester onto the surface decreased.

The mechanism of the ring-opening polymerization of lactide and glycolide

To obtain more insight in the ring-opening polymerization of lactones, complex formation of the initiators tetraphenyltin, stannous octoate, tin tetrachloride, aluminium bromide and triisobutylaluminium (TIBA), and the monomers l(−)-lactide, d,l-lactide and glycolide was studied by i.r.-spectroscopy. When equimolar benzene or toluene solutions of initiators and monomers were combined, only complexes of aluminium bromide and d,l-lactide or glycolide, and of TIBA and d,l-lactide or glycolide were observed. The complex formation was studied in detail by varying the initiator and monomer concentrations. From these results and theoretical considerations, it is concluded that complexes are formed by the coordination of a carbonyl oxygen of monomer and the aluminium atom of initiator. The corresponding polymers were formed when TIBA was used as an initiator. When AlBr, was used, polymers were obtained only when traces of water were added. It is concluded that in the case of AlBr 3 the actual initiating species is HBr and that the polymerization initiated with TIBA proceeds very probably through a coordinated insertion of the lactone monomer into the aluminium-carbon bond.

Soluble Bimetallic μ-Oxo-alkoxides. 8. Structure and Kinetic Behavior of the Catalytic Species in Unsubstituted Lactone Ring-Opening Polymerization

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSoluble Bimetallic μ-Oxo-alkoxides. 8. Structure and Kinetic Behavior of the Catalytic Species in Unsubstituted Lactone Ring-Opening PolymerizationT. Ouhadi, A. Hamitou, R. Jerome, and Ph. TeyssieCite this: Macromolecules 1976, 9, 6, 927–931Publication Date (Print):November 1, 1976Publication History Published online1 May 2002Published inissue 1 November 1976https://doi.org/10.1021/ma60054a009RIGHTS & PERMISSIONSArticle Views292Altmetric-Citations66LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (580 KB) Get e-Alerts Get e-Alerts