Surface and interaction characteristics of poly(styrene-b-4vinylpyridine) (S-4VP) and poly(styrene-b-methacrylic acid) (S-MAA) diblock copolymers were investigated by the method of inverse gas chromatography (IGC). Not surprisingly, the MAA segments were found to be acidic, while the polystyrene (PS) and the 4VP blocks were found to be basic, the 4VP moiety being the stronger base. For the S-4VP diblocks, when adsorbed onto particulates with acidic surfaces, the 4VP block is preferentially oriented to the substrate, leaving an air interphase which is enriched in PS. For the S-MAA diblock, at higher interphase thicknesses, the bulk and surface compositions became similar, and the interphases are non-isotropic with respect to local composition, and molecular conformation. For both diblocks, it was shown that the adsorbed layers form interphases in which the local composition varies with the adsorbed mass and the composition of the copolymer diblock. The effect was more pronounced when the strength of the acid/base interactions at the interface was increased. The experimental finding also permits the calculation of thicknesses for the adsorbed interphases (100-1000 A). / Proton nuclear magnetic resonance was used to determine the quantities of S-4VP diblocks in solution. In a selective solvent (toluene), it was found that surface interactions lead to preferential adsorption of the 4VP chain segments onto the particulates. Isotherms show that there is a direct correlation between the normalized equilibrium quantities of adsorbed copolymer diblocks and the length of the 4VP anchor. A linear relationship also was obtained between the equilibrium quantities per unit area of substrate, and the acid/base properties of the particulates. Using a published scaling model, good agreement was found between the experimental and predicted equilibrium quantities of adsorbed material. For these systems, it was demonstrated that the prefactor of the scaling law relation was directly related to the acid/base properties of the substrate, as expressed by the values of the acid/base surface indices obtained by IGC. / Composites based on PS and polychloroethylene were analyzed by dynamic mechanical thermal analysis and differential scanning calorimetry methods. The composites were formulated with four loading levels (2, 5, 20 and 35 wt %) of uncoated and coated (S-4VP modified) particulates. A chain overlap region at the boundary of the particulate was determined. The extent of this region was found to increase in parallel with the PS diblock segments, and with favorable acid/base interactions between the composite constituents.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.41354 |
| Date | January 1993 |
| Creators | Bossé, Francis |
| Contributors | Eisenberg, Adi (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: 001397691, proquestno: NN94588, Theses scanned by UMI/ProQuest. |
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