Polylactones. 28. Syndiotactic Poly(.beta.-D,L-hydroxybutyrate) by Ring-Opening Polymerization of .beta.-D,L-Butyrolactone with Butyltin Methoxides

Kricheldorf, Hans R.; Lee, Soo‐Ran; Scharnagl, Nico

doi:10.1021/ma00090a005

Cited by 61 publications

(54 citation statements)

References 4 publications

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“…From this point of view, the behavior of the spiro initiator completely agrees with that of other dibutyltin alkoxides. 13,15,24 Copolymerizations. Two series of copolymerizations were conducted to synthesize either copolyesters with a blocky or with a random sequence.…”

Section: Resultsmentioning

confidence: 99%

Polylactones. 40. Nanopretzels by Macrocyclic Polymerization of Lactones via a Spirocyclic Tin Initiator Derived from Pentaerythritol

Kricheldorf

Lee

1996

Macromolecules

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A spirocyclic initiator was synthesized from dibutyltin oxide and pentaerythritol. This spirocyclic distannoxane was characterized by elemental analyses, NMR spectroscopy, and a stoichiometric reaction with γ-thiobutyrolactone. -Caprolactone ( -CL) was polymerized in bulk at 70°C with variation of the monomer/initiator ratio. The molecular weights paralleled roughly the M/I ratio and high molecular weight poly( -CL) was obtained (Mw's up to 160 000). In contrast, homopolymerizations of -D,Lbutyrolactone ( -D,L-BL) in bulk at 75°C did not give high molecular weights (Mw up to 25 000) but high yields. The spiro-macrocyclic poly( -CL) was selectively ring-opened with dimercapto ethane, whereby a four-around star polyester was obtained. The end groups were identified by 1 H NMR spectroscopy. Furthermore, spirocyclic block copolymers were prepared by batchwise copolymerization of -D,L-BL and -CL. Furthermore, spirocyclic random copolyesters were obtained from mixtures of -D,L-butyrolactone and -CL. The block or random character of all copolylactones was characterized by 13 C NMR spectroscopy and DSC measurements. Only in the case of block copolymers, crystallized blocks of -CL were found. The structure of the end groups and the polymerization mechanism are discussed.

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Section: Resultsmentioning

confidence: 99%

Polylactones. 40. Nanopretzels by Macrocyclic Polymerization of Lactones via a Spirocyclic Tin Initiator Derived from Pentaerythritol

Kricheldorf

Lee

1996

Macromolecules

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“…chiral center like 3-hydroxybutyric acid; therefore, the DSC curves of PLA may have had similar phenomena, including the double-head endothermal peak to the DSC curves of poly(3-hydroxybutyrate)]. [42][43][44] However, after the second heating run, there was only a glass transition, which indicated that the certain crystalline copolymer wholly became amorphous.…”

Section: Thermal Properties and Crystallinity Of Poly(dl-lactide-chomentioning

confidence: 99%

Synthesis of poly(D,L‐lactic acid) modified by cholic acid via direct melt copolycondensation and its characterization

Wang

Zhao

Wang

et al. 2010

J of Applied Polymer Sci

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Myosin XVA is an unconventional myosin which has been implicated in autosomal recessive nonsyndromic hearing impairment (ARNSHI) in humans. In Myo15A mouse models, vestibular dysfunction accompanies the autosomal recessive hearing loss. Genomewide homozygosity mapping and subsequent fine mapping in two Turkish families with ARNSHI revealed significant linkage to a critical interval harboring a known deafness gene MYO15A on chromosome 17p13.1‐17q11.2. Subsequent sequencing of the MYO15A gene led to the identification of a novel missense mutation, c.5492G → T (p.Gly1831Val) and a novel splice site mutation, c.8968 − 1G → C. These mutations were not detected in additional 64 unrelated ARNSHI index patients and in 230 Turkish control chromosomes. Gly1831 is a conserved residue located in the motor domains of the different classes of myosins of different species. Molecular modeling of the motor head domain of the human myosin XVa protein suggests that the Gly1831Val mutation inhibits the powerstroke by reducing backbone flexibility and weakening the hydrophobic interactions necessary for signal transmission to the converter domain. © 2007 Wiley‐Liss, Inc.

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“…Moreover, they are more stable to oxygen and soluble in common organic solvents [9,11]. Also, the syndiotactic of desirable polyester can be effectively controlled using nBu 3 SnOMe [15,16]. However, there are a few reports on the kinetics of ROP of cyclic ester monomers initiated by nBu 3 SnOR [9,11], therefore their kinetic information is needed for more understanding on their catalytic behavior.…”

Section: Introductionmentioning

confidence: 99%

Kinetics and thermodynamics analysis for ring-opening polymerization of ε-caprolactone initiated by tributyltin n-butoxide using differential scanning calorimetry

Limwanich

Meepowpan

Nalampang

et al. 2014

J Therm Anal Calorim

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The bulk ring-opening polymerizations (ROP) of e-caprolactone (e-CL) initiated by synthesized tributyltin n-butoxide (nBu 3 SnOnBu) initiator were conducted at 120°C and the molecular mass and polydispersity index of poly(e-CL), PCL, were determined. The coordinationinsertion ROP of e-CL was confirmed by 1 H-NMR. The molecular mass of PCL was successfully controlled with monomer to initiator concentration ratio. The kinetics and thermodynamics of ROP were investigated by differential scanning calorimetry (DSC) using both non-isothermal and isothermal methods. From the non-isothermal method, the activation energy (E a ) of ROP of e-CL initiated by 1.0, 1.5, and 2.0 mol% of nBu 3 SnOnBu was derived from the method of Kissinger (78.3, 61.1, and 59.9 kJ mol -1 ) and Ozawa (82.8, 66.2, and 64.9 kJ mol -1 ). For isothermal method, the values of E a for these three concentrations of nBu 3 SnOnBu were 74.2, 65.8, and 62.0 kJ mol -1 , respectively. The first-order reaction model was employed to determine the apparent rate constant (k app ). The degree of aggregation (m) of nBu 3 SnOnBu in e-CL was also determined using isothermal method which confirmed its nonaggregated form. In addition, the activation enthalpy (DH = ) and entropy (DS = ) were estimated to be 70.5 kJ mol -1 and -100.3 J mol -1 K -1 by isothermal DSC. The Friedman, Kissinger-Akahira-Sunose, and Flynn-Wall-Ozawa isoconversional methods were also applied to non-isothemal DSC data to investigate the dependence of E a with monomer conversion (a). The results of all three methods were discussed and compared with isothermal and non-isothermal methods at 1.0 mol% of nBu 3 SnOnBu. The overall results demonstrate that DSC is a fast, convenient, and reliable method for studying the kinetics and thermodynamics of ROP of e-CL initiated by nBu 3 SnOnBu.

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Polylactones. 28. Syndiotactic Poly(.beta.-D,L-hydroxybutyrate) by Ring-Opening Polymerization of .beta.-D,L-Butyrolactone with Butyltin Methoxides

Cited by 61 publications

References 4 publications

Polylactones. 40. Nanopretzels by Macrocyclic Polymerization of Lactones via a Spirocyclic Tin Initiator Derived from Pentaerythritol

Polylactones. 40. Nanopretzels by Macrocyclic Polymerization of Lactones via a Spirocyclic Tin Initiator Derived from Pentaerythritol

Synthesis of poly(D,L‐lactic acid) modified by cholic acid via direct melt copolycondensation and its characterization

Kinetics and thermodynamics analysis for ring-opening polymerization of ε-caprolactone initiated by tributyltin n-butoxide using differential scanning calorimetry

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