Bulk Ring Opening Polymerization of <scp>L</scp>‐Lactide with Calcium methoxide

Dias, Marcos L.; Palermo, Luiz Carlos Magalhães; Silvino, Alexandre Carneiro

doi:10.1002/masy.200900101

Cited by 19 publications

(12 citation statements)

References 26 publications

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“…Kricheldorf and Serra showed that racemization efficiency in bulk polymerization of LA strongly depended on the metal, kind of ligand and obviously on temperature . Additionally, Dias et al indicated that in case of LA polymerization catalyzed with Ca(OMe) 2 , a decrease in the ratio of [LA] 0 /[Ca(OMe) 2 ] 0 caused an increment of racemization efficacy . Moreover, in case of LA polymerization many side reactions, for instance internal and external transesterification or chain transfer could take place .…”

Section: Introductionmentioning

confidence: 99%

Screening of metal catalysts influence on the synthesis, structure, properties, and biodegradation of PLA‐PBA triblock copolymers obtained in melt

Kundys

Plichta

Florjańczyk

et al. 2015

J. Polym. Sci. Part A: Polym. Chem.

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The synthesis of ABA type triblock copolymers comprising poly(1,4‐butylene adipate) macroinitiator and polylactide segments is described in this article. Acetylacetonates of various low‐toxic metals: Li, Mg, Ca, Zn, Fe, and Zr are used as catalysts. The course of polymerization, microstructure, thermal properties, and biodegradation of the copolymers obtained are analyzed based on the electronegativity of the metal used. The macroinitiator is completely incorporated into the major products, however, linear and cyclic lactide homopolymers and copolymers are present because of moisture presence and transesterification processes. The efficiency of side reactions depends on the catalyst used. The highest molar mass of copolymer is obtained with a Zr‐based catalyst. The efficacy of polylactide racemization is higher for catalysts comprising the metal of lower electronegativity. Under thermal degradation conditions the polylactide segment degrades before the macroinitiator one. The copolymers studied undergo faster biodegradation than polylactide and they can decompose in compost within 16 weeks. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1444–1456

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Section: Introductionmentioning

confidence: 99%

Screening of metal catalysts influence on the synthesis, structure, properties, and biodegradation of PLA‐PBA triblock copolymers obtained in melt

Kundys

Plichta

Florjańczyk

et al. 2015

J. Polym. Sci. Part A: Polym. Chem.

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“…Moreover, as its monomer is synthesized by the human body, PLA is bioabsorbable being an excellent choice for biomedical applications as the controlled drug release. The PGA is also hydrolytically degradable and its degradation products are nontoxic .…”

Section: Introductionmentioning

confidence: 99%

Influence of magnetic field on the dissolution profile of cotrimoxazole inserted into poly(lactic acid‐co‐glycolic acid) and maghemite nanocomposites

Pereira

Souza

Santana

et al. 2013

Polymer Engineering & Sci

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The antibiotic cotrimoxazole was associated with poly(lactic acid-co-glycolic acid) (PLGA) and maghemite, aiming to reach a controlled drug release system. PLGA was synthesized through the polycondensation of lactic acid and glycolic acid in an equimolar ratio, and maghemite was synthesized through the coprecipitation method. The drug cotrimoxazole was inserted in the composite through three different procedures: solution, fusion, and in situ to check the best insertion method. Several techniques were used to characterize the materials. The copolymer was characterized by nuclear magnetic resonance and size-exclusion chromatography. In addition, the maghemite, the composites containing the drug, and the polymer were characterized by Fourier transform infrared spectroscopy (FTIR) with attenuated total reflectance device, small-angle X-ray scattering, and magnetic force, this last according to the methodology developed by our group. The root mean square error was used to compare the FTIR spectra of the samples, proving that the fusion method was the best way to insert the drug and maghemite in the polymer. Therefore, composites containing the drug and the nanoparticles were prepared by the fusion method. These composites were used for dissolution profile studies, which were monitored with and without magnetic field, aiming to understand the influence of the magnetic field on the dissolution profile. The dissolution was monitored and quantified using the ultraviolet-visible spectrophotometry, following the United States Pharmacopeia (USP) method for cotrimoxazole tablets. Results demonstrated that nanocomposites presented a good magnetic force, able to keep the magnetic composite trapped in a specific place or tissue. The presence of the nanoparticles in the composites changed the kinetics of the drug release, as they constitute physical barriers to the drug diffusion, contributing to a sustained drug release process. Furthermore, in the presence of a magnetic field, the magnetic nanoparticles were able to perform a magnetic constriction of the material, making the drug release faster than in the absence of the magnetic field, which may be useful to perform a fine tuning of the system, allowing the easier adjustment of the speed and amount of released drug, useful to improve medical treatments and even the welfare of the patients.

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“…The polymers should be free from compounds potentially hazardous to human health. Because small amounts of catalyst will inevitably be trapped in the polymeric material, less toxic, biologically benign polymerization initiators such as organocatalysts6 as well complexes of magnesium,7–9 calcium,9, 10 zinc,8, 9 iron,5 titanium,11 or bismuth12 are receiving growing scientific interest.…”

Section: Introductionmentioning

confidence: 99%

Bismuth(III) Alkoxide Catalysts for Ring‐Opening Polymerization of Lactides and ϵ‐Caprolactone

Vuorinen

Lahcini

Hatanpää

et al. 2013

Macro Chemistry & Physics

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Homoleptic bismuth alkoxide complexes, Bi(OR) 3 [R = i Pr ( 1 ), t Bu ( 2 ), and CMe 2 i Pr ( 3 )], are used as catalysts in the ring-opening polymerization (ROP) of lactides. In contrast to 1 , two bulkier bismuth alkoxides, 2 and 3, show high activity in the ROP of lactides in toluene at 75 ° C. Notably, Bi III alkoxides 2 and 3 are more active in lactide ROP than Sn II octoate activated with n -butanol under identical reaction conditions. Bismuth alkoxides 2 and 3 exhibit a living behavior in the ROP of lactides that is demonstrated both in homopolymerization and in a polymerization resumption experiment. Polymerization of rac -lactide using 2 and 3 yields polylactide with a slight heterotactic bias. In addition, 2 is an effi cient initiator for the ROP of ε -caprolactone in bulk at 120 ° C. Variation of the monomer-to-catalyst ratio yielded poly( ε -caprolactone) with M n s up to 120 000 g mol − 1 in corrected gel-permeation chromatography (GPC) data.

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Bulk Ring Opening Polymerization of L‐Lactide with Calcium methoxide

Cited by 19 publications

References 26 publications

Screening of metal catalysts influence on the synthesis, structure, properties, and biodegradation of PLA‐PBA triblock copolymers obtained in melt

Screening of metal catalysts influence on the synthesis, structure, properties, and biodegradation of PLA‐PBA triblock copolymers obtained in melt

Influence of magnetic field on the dissolution profile of cotrimoxazole inserted into poly(lactic acid‐co‐glycolic acid) and maghemite nanocomposites

Bismuth(III) Alkoxide Catalysts for Ring‐Opening Polymerization of Lactides and ϵ‐Caprolactone

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