Application of zirconium (IV) acetylacetonate to the copolymerization of glycolide with ε-caprolactone and lactide

Bero, Maciej; Dobrzyński, P.; Kasperczyk, Janusz

doi:10.1007/s002890050444

Cited by 45 publications

(31 citation statements)

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“…These studies have primarily been limited to the partial assignment of local sequence within otherwise random copolymers. 34,36,39,40,45,55-58 Our approach to preparing PLGAs, which allows for nearly perfect sequence and stereocontrol, greatly expands the database and offers, thereby, a significant advance in the understanding of PLGA NMR data as well as some interesting new conclusions of a more general nature pertaining to sequenced copolymers.…”

Section: Introductionmentioning

confidence: 99%

New Insights into Poly(lactic-co-glycolic acid) Microstructure: Using Repeating Sequence Copolymers To Decipher Complex NMR and Thermal Behavior

2010

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Sequence, which Nature uses to spectacular advantage, has not been fully exploited in synthetic copolymers. To investigate the effect of sequence and stereosequence on the physical properties of copolymers a family of complex isotactic, syndiotactic and atactic repeating sequence poly(lactic-co-glycolic acid) copolymers (RSC PLGAs) were prepared and their NMR and thermal behavior was studied. The unique suitability of polymers prepared from the bioassimilable lactic and glycolic acid monomers for biomedical applications makes them ideal candidates for this type of sequence engineering. Polymers with repeating units of LG, GLG and LLG (L = lactic, G = glycolic) with controlled and varied tacticities were synthesized by assembly of sequence specific, stereopure dimeric, trimeric and hexameric segmer units. Specifically labeled deuterated lactic and glycolic acid segmers were likewise prepared and polymerized. Molecular weights for the copolymers ranged from Mn = 12-40 kDa by size exclusion chromatography in THF. Although the effects of sequence-influenced solution conformation were visible in all resonances of the 1H and 13C NMR spectra, the diastereotopic methylene resonances in the 1H NMR (CDCl3) for the glycolic units of the copolymers proved most sensitive. An octad level of resolution, which corresponds to an astounding 31-atom distance between the most separated stereocenters, was observed in some mixed sequence polymers. Importantly, the level of sensitivity of a particular NMR resonance to small differences in sequence was found to depend on the sequence itself. Thermal properties were also correlated with sequence.

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Section: Introductionmentioning

confidence: 99%

New Insights into Poly(lactic-co-glycolic acid) Microstructure: Using Repeating Sequence Copolymers To Decipher Complex NMR and Thermal Behavior

2010

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“…eCaprolactone from Fluka, Switzerland, was dried and distilled under argon prior to use. Copolymerisation of glycolide with e-caprolactone in the molar ratios 0.8 glycolide/0.2 e-caprolactone (0.8Gly/0.2Cap) and 0.2 glycolide/0.8 e-caprolactone (0.2Gly/0.8Cap) was carried out in bulk at 373 K using zirconium (IV) acetylacetonate as an initiator [5]. The product was degassed and sealed on a vacuum line, ground, shaken with methyl alcohol to remove unreacted monomers, and dried under vacuum at 323 K. Liquid chromatography using a Waters ALC/ GPC 3 m apparatus gave the molecular weights as 80,000 for 0.2Gly/0.8Cap and 100,000 for 0.8Gly/0.2Cap.…”

Section: Methodsmentioning

confidence: 99%

1H and 13C NMR Studies of Molecular Dynamics in the Biocopolymer of Glycolide and ε-Caprolactone

Nozirov

Szcześniak

Fojud

et al. 2002

Solid State Nuclear Magnetic Resonance

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“…The α-CH 2 and ε-CH protons in the CL units and the CH 2 2 protons in the G units are seen to be particularly sensitive to this. The bands at 2.4 and 4.1 ppm, corresponding to the α-CH and ε-CH 2 2 protons in the CL units, respectively are split into two quite distinct triplets adjacent to one another suggesting randomization of the CL units in the copolyester chains [28,29]. The band at 4.9 ppm corresponding to the CH 2 protons of the G units also show different resonance lines indicating various sequences of lactyl units (half-lactide units) and glycolyl units (half-glycolide units) [30].…”

Section: Chain Microstructure Of Diblock Copolymersmentioning

confidence: 99%

Synthesis and characterization of methoxy poly(ethylene glycol)-b-poly(DL-lactide-co-glycolide-co-ε-caprolactone) di block copolymers: Effects of block lengths and compositions

et al. 2007

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Methoxy poly(ethylene glycol)-b-poly(D,L-lactide-co-glycolide-co-ε-caprolactone) diblock copolymers, designated as MPEG-b-PDLLGCL, with different MPEG block lengths and DLL:G:CL ratios were synthesized via ring-opening polymerization in bulk using MPEG and stannous octoate as the initiating system. The diblock copolymers were characterized using a combination of FT-IR, 1 H-NMR, GPC and DSC. The percentage yields of the diblock copolymers were in excess of 90%. 1 H-NMR analysis confirmed that the PDLLGCL blocks contained at least some random character. From their DSC curves, the diblock copolymers were amorphous in morphology. Their glass transition temperatures decreased as the MPEG block length increased and as G and CL units were incorporated.

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Application of zirconium (IV) acetylacetonate to the copolymerization of glycolide with ε-caprolactone and lactide

Cited by 45 publications

References 1 publication

New Insights into Poly(lactic-co-glycolic acid) Microstructure: Using Repeating Sequence Copolymers To Decipher Complex NMR and Thermal Behavior

New Insights into Poly(lactic-co-glycolic acid) Microstructure: Using Repeating Sequence Copolymers To Decipher Complex NMR and Thermal Behavior

1H and 13C NMR Studies of Molecular Dynamics in the Biocopolymer of Glycolide and ε-Caprolactone

Synthesis and characterization of methoxy poly(ethylene glycol)-b-poly(DL-lactide-co-glycolide-co-ε-caprolactone) di block copolymers: Effects of block lengths and compositions

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