The effect of the molecular weight distribution of both the soluble and the insoluble blocks on the solution self-assembly of the amphiphilic block copolymer polystyrene-block-poly(acrylic acid) was studied. Copolymers of a variety of block lengths but with narrow molecular weight distributions were synthesized by sequential anionic synthesis. Mixing two or more copolymers of differing block length (while the second block length was identical) artificially increased the polydispersity index (PDI) of one block. Self-assembly was induced by adding water slowly to a copolymer solution until a desired solvent composition was attained. The resulting aggregates were compared using transmission electron microscopy and dynamic light scattering. / The first experiments, presented in chapter 2, studied the effect of the corona (PAA) polydispersity on the size of vesicular aggregates. For a constant solvent composition and copolymer concentration, the size of the vesicles was generally found to decrease with increasing PAA polydispersity. In chapter 3, a partial phase diagram of morphology as a function of water content and PAA polydispersity is presented. The phase boundaries between spheres and rods, and rods and vesicles were found to shift to lower water contents with increased PAA polydispersity. / While chapters 2 and 3 show that the PAA polydispersity affects both the morphology and the size of vesicles, chapter 4 presents work that indicates that the shape of the PAA molecular weight distribution plays an important part in determining the degree to which the PAA polydispersity affects the morphology. A subsequent study also shows that the molecular weight distribution effect only occurs when the relative PAA/PS block length ratio is low. / The polystyrene molecular weight distribution studies, presented in chapter 5, show that the opposite effect to that of the PAA molecular weight distribution occurs with an increase in the PS PDI. The morphological boundary from spheres to rods was found to move to higher water contents with an increase in PS PDI. Even at very high water contents, where vesicles are usually found for low molecular weight distribution samples, only spherical micelles were found for the samples with increased PS PDI.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.85098 |
| Date | January 2004 |
| Creators | Terreau, Owen L. |
| 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: 002173412, proquestno: AAINR06344, Theses scanned by UMI/ProQuest. |
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