The principal objectives of this thesis are to introduce a new method, colloidal particle scattering (CPS), to measure colloidal and surface forces, and to demonstrate various applications of this method. CPS determines particle-particle interaction forces through creating particle collisions and extracting the interaction forces from the degree of asymmetry of the collision trajectories. Since the force to deflect a micron-sized particle is much smaller than that to deform a macroscopic spring or cantilever used in a commercial force apparatus, this new technique increases the resolution of force determination by four orders of magnitude. / Based on the CPS principles, we have built a force apparatus called "microcollider". It successfully determined the van der Waals forces and the electrostatic force between two 5 $ mu$m latex spheres at different salt concentrations. A "hairy" latex model was introduced to explain the measured van der Waals forces which are weaker than those predicted by theory assuming smooth latex surfaces. This is consistent with other experimental findings about the surfaces of latex particles. / A similar "hairy" model was applied to determine the adsorption layer thicknesses of two triblock copolymers adsorbed on latex particles. The results show that the configuration of the buoy block composed of polyethylene oxide (PEO) is more extended than a random PEO coil, which agrees with theoretical predictions. Moreover, excellent quantitative agreement between the adsorption layer thicknesses determined by CPS and other methods has been found. / Dynamic steric interactions between two high molecular weight PEO adlayers have also been studied. Both the elastic modulus and the adsorption layer thickness were determined. The results show that a thick layer has a lower elastic modulus than a thin one composed of the same polymer. This implies that an extended loop/tail structure in a thick layer is less stiff than a flat compact one in a thin layer, which is consistent with theory. / In addition, the microcollider can accurately determine particle-wall interactions as well. A rather weak electrokinetic lift force was measured. The results are in good agreement with the solutions rigorously derived from two new theories.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.40469 |
| Date | January 1996 |
| Creators | Wu, Xin, 1967- |
| Contributors | Ven, T. G. M. van de (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: 001537844, proquestno: NN19786, Theses scanned by UMI/ProQuest. |
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