title: Minimization of residual tin in the controlled Sn(II)octoate-catalyzed polymerization of epsilon-caprolactone.
abstract: 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 an efficiency equal to or better than that on normal tissue culture plastic.
authors.affiliation: Department of Fibre and Polymer Technology, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Stjerndahl
authors.forename: A
authors.initials: A
authors.lastname: Finne-Wistrand
authors.forename: A-C
authors.initials: AC
authors.lastname: Albertsson
authors.forename: C M
authors.initials: CM
authors.lastname: Bäckesjö
authors.forename: U
authors.initials: U
authors.lastname: Lindgren
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D002208:Caproates / Q000737:chemistry*; D002460:Cell Line; D049109:Cell Proliferation; D007783:Lactones / Q000737:chemistry*; D008422:Materials Testing; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000502:physiology; D051379:Mice; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D014001:Tin / Q000737:chemistry*; D054457:Tissue Scaffolds / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D002208:Caproates; D007783:Lactones; D011108:Polymers; C419565:2-ethylhexanoic acid tin(II) salt; C121056:caprolactone; D014001:Tin