Graft copolymers using biodegradable and biocompatible bacterial poly([ R]-3-hydroxybutyrate) blocks were synthesized and tested as biomaterial candidates for orthopaedic surgery applications. Low molecular weight poly([ R]-3-hydroxyalkanoates), namely poly([R]-3-hydroxybutyrate), poly([R]-3-hydroxyvalerate), and their copolymers poly([ R]-3-hydroxybutyrate-co-[R]-3-hydroxyvalerate), were prepared by thermal degradation in the melt at 190°C. The chemical composition of the oligomers was well-defined, featuring the same repeat unit as their high molecular weight analogues, a carboxylic acid end, and an alkenyl end mostly in the trans configuration (crotonate-type). Increase in the reaction temperature, time, or [R]-3-hydroxyvalerate content decreased the molecular weight of the products. Methacrylic macromonomers of PHB were obtained by functionalization of the oligomers at the carboxyl end, and copolymerized with methyl methacrylate. Two free radical polymerization methods were employed: conventional free radical and a controlled free radical polymerization, Atom Transfer Radical Polymerization. Kinetics of the copolymerizations were studied, and the copolymerization behavior of the comonomers was shown to change with the comonomer feed composition. This would have resulted in variable graft copolymer microstructures. Graft copolymers produced by conventional free radical copolymerization were incorporated in commercial acrylic (poly(methyl methacrylate)-based) bone cement formulations. Cements with formulations containing 6.6-6.7, and 13.5 wt.-% of PMMA-graft-PHB were prepared. The morphology of the graft copolymer particles was suggested to influence the processability of the modified cement. The cements were found rather porous, with average porosities of 13.5 to 16.9%. Nevertheless compression strengths were quite similar to those found for the reference material, pure Antibiotic SimplexRTM, and met the ASTM requirements on acrylic b
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.85631 |
| Date | January 2004 |
| Creators | Nguyen, Sophie |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Chemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002209797, proquestno: AAINR12917, Theses scanned by UMI/ProQuest. |
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