The in situ, equimolar, trimethylaluminum/H$ sb2$O catalyst was used for the ring opening polymerization of racemic $ beta$-butyrolactone, $ beta$-heptanolactone and $ beta$-nonanolactone to form synthetic analogues of the naturally occurring family of biodegradable poly((R) -$ beta$-hydroxyalkanoate) polymers. This catalyst was found to produce both a better yield and a higher molecular weight of a high isotactic, primarily crystalline fraction of poly($ beta$-(R,S) -hydroxybutyrate) than the conventional in situ, equimolar triethylaluminum/H$ sb2$O catalyst. A mechanically tougher, less isotactic and less crystalline fraction of lower molecular weight and a largely amorphous fraction of even lower molecular weight were also isolated and characterized. / Biodegradation of solid films of synthetic poly($ beta$-(R,S) -hydroxybutyrate) in the presence of an "extracellular" poly($ beta$-(R) -hydroxybutyrate) depolymerase was found to be dependent on accessibility of the enzyme to the (R) linkages along the polymer chain. The semicrystalline fraction was the most susceptible to degradation whereas the high crystallinity fraction showed little degradation and the low crystallinity fraction only showed limited degradation early in the incubation period. / Synthetic poly($ beta$-(R,S) -hydroxyheptanoate) and poly($ beta$-(R,S) -hydroxynonanoate) polyesters were prepared for the first time and the whole product was predominantly isotactic. It was found to have comparable physical properties as the biosynthetic materials, which are only available as terpolymers. Evidence for paracrystalline ordering relating to the organization of the side chains and formation of liquid crystalline-like phases was observed.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.41256 |
| Date | January 1993 |
| Creators | Jesudason, Jeyarajan Joseph |
| Contributors | Marchessault, R. H. (advisor) |
| 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: 001392451, proquestno: NN91723, Theses scanned by UMI/ProQuest. |
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