The chiral nematic texture of a number of anisotropic cellulosic systems is revealed with the help of transmission electron microscopy (TEM) and atomic force microscopy (AFM). TEM and AFM examination of sections of cellulose films, ethyl cellulose (EC) films, ethyl methyl cellulose (EMC) films, cellulose acetate (CA) films and (6-O-trityl 2,3-O-hexyl) cellulose (C(Tr)(He))1 films showed periodicities which are characteristic of chiral nematic arrangements. Those periodicities are related to the helicoidal pitch of such organisations. Furthermore, specific structural defects were observed in sections of the chiral nematic films. These defects are associated with a parabolic focal conic texture. / Chiral nematic gels were produced by $ gamma$-ray irradiation of (hydroxypropyl)cellulose (HPC) mesophases in water or methanol. Solid/liquid extraction performed on irradiated HPC films and mesophases allow us to evaluate their respective degrees of crosslinking. Optical microscopy, TEM and AFM results showed that a chiral nematic order is preserved in the crosslinked mesophases. / Helicoidal suspensions of cellulosic microfibrils were prepared by acidic hydrolysis of wood pulp. Solid films, dried from these microfibril suspensions, show that the chiral nematic arrangement of the cellulosic microfibrils can be maintained in a solid material. Basic morphological data on chiral nematic films made from cellulosic microfibrils are given in this thesis. / The origin of the strong contrast observed in TEM images of sections of chiral nematic cellulosic materials is discussed. We also introduce novel sample preparation techniques for microscopic observation.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.29030 |
| Date | January 1995 |
| Creators | Giasson, Julie |
| Contributors | Gray, Derek G. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | French |
| 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: 001472717, proquestno: NN08104, Theses scanned by UMI/ProQuest. |
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