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Large scale synthesis of polyesters with low amount of residual tin
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
2007 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [sv]

Användningen av resorberbara polymerer för applikationer inom vävnadsersättning har ökat markant under de senaste decennierna. Tekniken innebär att celler får växa på ett polymert bärarmaterial och på så sätt återskapa skadad vävnad, och är ett lovande alternativ till många av de implantat som används idag. Alifatiska polyestrar, syntetiserade med ringöppningspolymerisation, har intagit en särställning som material för dessa applikationer.

I den här avhandlingen har ε-kaprolakton syntetiserats med hjälp av två olika tennföreningar, varav en initiator och en katalysator, med målet att optimera förhållandena för industriell tillämpning. Storleken och renheten på polymerisationen, samt resthalten av tenn i materialet studerades.

ε-kaprolakton polymeriserades i odestillerad toluen med 1-di-n-butyl-1-stanna-2,5-dioxacyclopentan som initiator. Variation av batchstorlekarna till 5, 20 och 50 g hade ingen påverkan på slutlig omsättning, molekylvikt eller polydispersitet. Genom att reagera polymeren med 1,2-etanditiol minskade resthalten av tenn i materialet från 1000 ppm till 23.

Den kommersiella katalysatorn Sn (II) 2-etylhexanoat användes också för att polymerisera ε-kaprolakton. Förhållandet katalysator:monomer varierades mellan 1:1000, 1:10000 och 1:20000, med bibehållen kontroll av reaktionen och molekylvikt. Genom att minska halten katalysator erhölls ett material med endast 5 ppm tenn. Celltillväxten på materialen studerades också, med resultatet att celler växer lika effektivt på polymeren som de gör när de odlas med enbart odlingmediet.

Abstract [en]

The use of bioresorbable polymers for tissue engineering applications has gained increased interest during the last decades. This promising technique, in which cells are regenerated on artificial polymeric scaffolds, is an alternative to transplantation of donor tissue or organs. Aliphatic polyesters, synthesized by ring-opening polymerization, have a leading role as the material of choice for these applications.

In this thesis, ring-opening polymerization of ε-caprolactone was performed with two different tin-containing compounds, one initiator and one catalyst, with the purpose of optimizing the conditions for industrial processes. The batch size and purity of the synthesis, as well as the residual amount of tin in the polymers, were studied.

Polymerization of ε-caprolactone in undistilled toluene with 1-di-n-butyl-1-stanna-2,5-dioxacyclopentane as initiator was successfully performed in batches of 5, 20, and 50 g with no differences in the final conversion, molecular weight, or polydispersity. By using a purification procedure in which the polymer was reacted with 1,2-ethanedithiol, the residual amount of tin was significantly reduced from over 1000 ppm to 23 ppm in this material.

Poly(ε-caprolactone) was also synthesized using the commercially available catalyst tin (II) 2-ethylhexanoate. Three different catalyst:monomer ratios were used: 1:1000, 1:10000, and 1:20000, without influencing the control of the reaction. By lowering the initial amount of catalyst in the polymerization a residual tin content of 5 ppm was reached, without the need for additional purification procedures. For this polymerization system, it was thus concluded that a catalyst:monomer ratio of 1:10000 or lower is required to achieve a tin content less than 20 ppm in the polymer. These materials were also tested in a cell proliferation study with mesenchymal stem cells from mouse. The results showed that cells grew on the biomaterial with an efficiency equal to or better than obtained with normal tissue culture plastic.

Place, publisher, year, edition, pages
Stockholm: KTH , 2007. , 29 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2007:41
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-4446ISBN: 978-91-7178-721-7 (print)OAI: oai:DiVA.org:kth-4446DiVA: diva2:12335
Presentation
2007-06-15, E3, KTH, Lindstedtsvägen 3, Stockholm, 08:15
Opponent
Supervisors
Note
QC 20101117Available from: 2007-06-20 Created: 2007-06-20 Last updated: 2010-11-17Bibliographically approved
List of papers
1. Industrial utilization of tin-initiated resorbable polymers: synthesis on a large scale with a low amount of initiator residue
Open this publication in new window or tab >>Industrial utilization of tin-initiated resorbable polymers: synthesis on a large scale with a low amount of initiator residue
2007 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 3, 937-940 p.Article in journal (Refereed) Published
Abstract [en]

This article presents the successful large-batch synthesis of a resorbable polymer with a minimal amount of residual tin. Ring-opening polymerization of ε-caprolactone was performed in toluene, with a tin (IV) alkoxide as the initiator. A number of parameters were varied in order to study the polymerization with respect to the purity of solvent, batch size, and the residual amount of tin in the polymers. The synthesis of ε-caprolactone in undistilled toluene with 1-di-n-butyl-1-stanna-2,5-dioxacyclopentane as the initiator was successfully performed in batches of 5, 20, and 50 g with no differences in the final conversion, molecular weight, or molecular-weight distribution. The residual amount of tin was significantly reduced from over 1000 to 23 ppm. This study examines the industrial utility of the materials regarding the size and purity of the synthesis.

Keyword
Initiators (chemical), Molecular weight distribution, Polycaprolactone, Ring opening polymerization, Solvents, Synthesis (chemical), Tin, Toluene
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-7344 (URN)10.1021/bm0611331 (DOI)000244798600023 ()2-s2.0-33947695273 (Scopus ID)
Note
QC 20100920Available from: 2007-06-20 Created: 2007-06-20 Last updated: 2017-12-14Bibliographically approved
2. Minimization of residual tin in the controlled Sn(II)octoate-catalyzed polymerization of ε-caprolactone
Open this publication in new window or tab >>Minimization of residual tin in the controlled Sn(II)octoate-catalyzed polymerization of ε-caprolactone
Show others...
2008 (English)In: Journal of Biomedical Materials Research - Part A, ISSN 1549-3296, Vol. 87A, no 4, 1086-1091 p.Article in journal (Refereed) Published
Abstract [en]

By using less catalyst in the ring-opening polymerization of epsilon-caprolactone, a residual tin content of 5 ppm was reached without the need for additional purification. The initial amount of tin (II) 2-ethylhexanoate [Sn(Oct)(2)] was varied using catalyst:monomer ratios of 1:1000, 1:10,000, and 1:20,000. The impact on the final conversion, reaction control, average molecular weight, and polydispersity was studied. The amount of Sn(Oct)(2) could be significantly, reduced without influencing the reaction results. The residual amount of tin was reduced from 176 ppm with a catalyst:monomer ratio of 1:1000 in the polymer, to 5 ppm with the ratio 1:10,000. It was thus concluded that a catalyst:monomer ratio of 1:10,000 or lower is required to achieve a polymer with tin content Suitable for biomedical applications. The materials were also tested in a proliferation study with mesenchymal stem cells from mouse. Porous scaffolds were fabricated from the polymers, using a salt leaching technique, and the cell growth on the porous scaffolds as well as on homogeneous films was determined by light absorbance measurements. In this study, the cell proliferation results showed that cells could grow on all polymers with ail efficiency equal to or better than that on normal tissue Culture plastic.

Keyword
ring-opening polymerization, poly(epsilon-caprolactone), tin (II) ethylhexanoate, residual tin, cell proliferation
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-7345 (URN)10.1002/jbm.a.31733 (DOI)000261075600027 ()2-s2.0-56749150882 (Scopus ID)
Note
QC 20100922. Uppdaterad från Submitted till Published (20100922).Available from: 2007-06-20 Created: 2007-06-20 Last updated: 2010-09-22Bibliographically approved

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