Kinetics of Elementary Reactions in Cyclic Ester Polymerization

Penczek, Stanisław; Duda, Andrzej; Szymański, Ryszard; Baran, Jolanta; Libiszowski, Jan; Kowalski, Adam

doi:10.1007/978-94-011-4627-2_18

Cited by 4 publications

(9 citation statements)

References 34 publications

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“…22,30 -33 Very recent works by Penczek et al 34 and by some of us 35 tend to show that Sn(Oct) 2 would react reversibly with hydroxyl compounds present in the reaction medium, e.g., residual lactic acid or the hydrolytically opened lactide, so as tin alkoxides such as (RO) nSn(Oct) 2-n (with n ϭ 1 or 2) would be made available even at very low steady state concentration. These tin alkoxide species would initiate the polymerization of lactide through the "coordinationinsertion" mechanism known for similar metal alkoxides of Al, Zr, Ti, and Sn.…”

Section: Kineticsmentioning

confidence: 97%

Beneficial effect of triphenylphosphine on the bulk polymerization of L , L ‐lactide promoted by 2‐ethylhexanoic acid tin (II) salt

Degée

Dubois

Jacobsen

et al. 1999

J. Polym. Sci. A Polym. Chem.

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Section: Kineticsmentioning

confidence: 97%

Beneficial effect of triphenylphosphine on the bulk polymerization of L , L ‐lactide promoted by 2‐ethylhexanoic acid tin (II) salt

Degée

Dubois

Jacobsen

et al. 1999

J. Polym. Sci. A Polym. Chem.

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“…Strukturê otrzymanych produktów homopolimeryzacji CL i LA potwierdzono metodami spektroskopowymi: 1 H NMR i 13 C NMR oraz IR. Uzyskane widma by³y zgodne z danymi literaturowymi [33][34][35][36][37][38][39].…”

Section: Struktura Produktówunclassified

“…Mechanizm polimeryzacji wspomnianych monomerów w obecnooeci SnOct 2 jest wci¹¿ tematem licznych dyskusji. Obecnie proponuje siê dwa mechanizmy wspomnianej polimeryzacji: aktywowanego monomeru lub koñca ³añcucha [33][34][35][36][37][38][39]. W mechanizmie aktywowanego monomeru przyjmuje siê, ¿e SnOct 2 tworzy kompleks z monomerem, a zaktywowany w ten sposób monomer ulega reakcji podstawienia nukleofilowego grup¹ hydroksylow¹ koinicjatora (alkoholu, hydroksykwasu, wody) lub rosn¹cej makrocz¹steczki.…”

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Evaluation of residual tin in synthesized aliphatic biomedical polyesters by electrothermal atomic absorption spectroscopy

Sobczak¹,

Żółtowska²,

Jaklewicz³

et al. 2010

Polimery

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Oznaczanie pozosta³ooeci cyny w syntetyzowanych biomedycznych poliestrach alifatycznych metod¹ elektrotermicznej absorpcyjnej spektrometrii atomowej Streszczenie-Metod¹ polimeryzacji z otwarciem pieroecienia, katalizowanej 2-etyloheksanianem cyny (SnOct 2) otrzymano cykliczne poliestry: polilaktyd (PLA) i poli(e-kaprolakton) (PCL). Uzyskane produkty poddawano procesowi kilkakrotnego oczyszczania z pozosta³ooeci cynoorganicznego katalizatora. Zawartooeae Sn w polimerach, po ka¿dym kolejnym oczyszczaniu, oznaczano za pomoc¹ elektrotermicznej absorpcyjnej spektrometrii atomowej (ET-AAS). Wyniki analiz dyskutowano uwzglêdniaj¹c wymagania Farmakopei Europejskiej dotycz¹ce dopuszczalnej zawartooeci cyny w biomedycznych poliestrach alifatycznych. Stwierdzono, ¿e czterokrotne oczyszczanie produktu polireakcji pozwala na obni¿enie poziomu stê¿enia Sn o 3 rzêdy wielkooeci, do wartooeci mniejszych ni¿ okreoelone przez Farmakopeê dla materia³ów maj¹cych kontakt z krwi¹, ponadto operacje te nie powoduj¹ degradacji polimeru. S³owa kluczowe: poliestry alifatyczne, polilaktyd, poli(e-kaprolakton), polimery biomedyczne, elektrotermiczna absorpcyjna spektrometria atomowa. DETERMINATION OF RESIDUAL TIN IN SYNTHESIZED ALIPHATIC BIOMEDICAL POLY-ESTERS BY ELECTROTHERMAL ATOMIC ABSORPTION SPECTROSCOPY Summary-The synthesis of the aliphatic polyesters-polylactide (PLA) and poly (e-caprolactanes) (PCL) in the ring-opening polymerization of cyclic esters in the presence tin(II) 2-ethylhexanoate (SnOct 2) has been presented. The obtained products were subjected to multiple purification procedures to remove residual organo-tin catalyst (Tables 2 and 3). The tin content in the polyesters was then determined by Electrothermal Atomic Absorption Spectroscopy (ET-AAS) (Tables 3 and 4) after each purification process. The results of the analysis were discussed taking into consideration the requirements placed by the European Pharmacopoeia regarding the amount of tin allowed in aliphatic biomedical polyesters. It was confirmed, that a four-stage purification of the polyreaction product led to a threefold decrease in the concentration of tin to a level less than the value required by Pharmacopoeia for materials designated for contact with blood. Moreover, the purification process did not generate any degradation of the polymer.

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“…There is little mention of the influence of coinitiators on the properties of gas‐phase‐polymerized products in the literature. There are, however, a few references to the synthesis and properties of emulsion, bulk, suspension, and (especially) photoinitiated polymerized products with coinitiators 1–16. Costela et al1 investigated the photophysics, photochemistry, and polymerization activity of p ‐nitronaphthylaniline (NNA) as an initiator in the presence of N,N ‐dimethylaniline (DMA) as a coinitiator for the preparation of poly(lauryl acrylate).…”

Section: Introductionmentioning

confidence: 99%

“…They established the relationships between the excitation energy transfer of NNA and the influence of the initiator on the photosensitized generation of free radicals derived from the coinitiator, DMA, which induced the photoreduction of NNA in a very low quantum yield. Penczek et al2 found that Sn 2+ dicarboxylate (dioctotate) required a coinitiator to initiate polymerization, and both kinetic and spectroscopic evidence indicated that the propagation proceeded on the SnOR bonds. Bu 2 SnO, dissolved in Bu 4 Sn with the addition of benzyl alcohol as a coinitiator, was used as the main initiator in the polymerization of poly(ϵ‐caprolactone) to yield benzyl ester chain ends 3…”

Section: Introductionmentioning

confidence: 99%

Solution properties of gas‐phase‐polymerized sodium acrylate microparticles. I. Influence of coinitiators

Sanderson¹,

Sadiku²

2002

J of Applied Polymer Sci

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A partially neutralized sodium acrylate (NaAc) monomer was polymerized in the gas phase in the presence of ammonium peroxydisulfate [(NH 4 ) 2 S 2 O 8 ] as the primary initiator and zinc acetate (ZnAc) as the coinitiator. The effect of the coinitiator on the solution properties of the spray-polymerized product was investigated for the conversion percentage as a function of (1) the primary initiator (NH 4 ) 2 S 2 O 8 concentration, with the concentration (14.8% with respect to the monomer) of the coinitiator kept constant; (2) the coinitiator (ZnAc) concentration, with the primary initiator concentration (4% with respect to the monomer) kept constant; and (3) the reaction temperature. The viscosity of the product as a function of the coinitiator concentration was also investigated. The conversion percentage of gas-phase-polymerized NaAc increased by approximately 8% (i.e., from 91.6 to 99.3%) with an increasing (NH 4 ) 2 S 2 O 8 concentration (0.5-5% with respect to the monomer). The conversion percentage as a function of the coinitiator concentration (0 -15% with respect to the monomer) increased by 25% (from 75 to 100%). When the concentrations of the initiators (NH 4 ) 2 S 2 O 8 and ZnAc were kept constant at 4 and 14.8% (with respect to the monomer), respectively, the conversion increased from 48 to 83% when the reaction temperature was increased from 100 to 140°C. The viscosity (at 20°C) of sodium polyacrylate decreased with an increasing coinitiator concentration. The relative rate of polymerization, as a function of the pH of the polymer, showed a minimum at pH Ϸ 6 and subsequently increased steeply, reaching a plateau at pH Ϸ 11; it then decreased again very sharply.

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Kinetics of Elementary Reactions in Cyclic Ester Polymerization

Cited by 4 publications

References 34 publications

Beneficial effect of triphenylphosphine on the bulk polymerization of L , L ‐lactide promoted by 2‐ethylhexanoic acid tin (II) salt

Beneficial effect of triphenylphosphine on the bulk polymerization of L , L ‐lactide promoted by 2‐ethylhexanoic acid tin (II) salt

Evaluation of residual tin in synthesized aliphatic biomedical polyesters by electrothermal atomic absorption spectroscopy

Solution properties of gas‐phase‐polymerized sodium acrylate microparticles. I. Influence of coinitiators

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