Modulating Electro-osmotic Flow with Polymer Coatings

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dc.contributor.authorHickey, Owen
dc.date.accessioned2012-01-12T17:17:49Z
dc.date.available2012-01-12T17:17:49Z
dc.date.created2012
dc.date.issued2012
dc.identifier.urihttp://hdl.handle.net/10393/20554
dc.identifier.urihttp://dx.doi.org/10.20381/ruor-5166
dc.description.abstractMicro- and nano-fluidic devices represent an exciting field with a wide range of possible applications. These devices, typically made of either silica or glass, ionize when placed in contact with water. Upon the application of an electric field parallel to the wall, a flow is produced by the charged walls called the electro-osmotic flow (EOF). Since electric fields are so often used as the driving force in these devices, EOF is an extremely common phenomenon. For this reason it is highly desirable to be able to control EOF in order to optimize the functioning of these devices. One method which is quite common experimentally is the modification of the surface using polymer coatings. These coatings can be either adsorbed or grafted, and charged or neutral. The first part of this thesis looks at the role of neutral adsorbed polymer coatings for the modulation of EOF. Specifically our simulation results show that for adsorbed coatings made from a dilute polymer solution the strongest quenching of EOF is found for an adsorption strength at the phase transition for adsorption of the polymers. Further evidence is presented that shows that by using a high density of polymer solution and a polymer which has a strong attraction to the surface a very thick polymer layer can be created. Next the case of charged grafted polymer coatings is examined. The variation of the EOF with respect to several key parameters which characterize the polymer coating is investigated and compared to theory. The prediction that the electrophoretic velocity of the polymers is the same as the EOF generated by a coating made up of the same polymers is found to be false though the two values are quite close. The last section presents results which show how hydrodynamic interactions in charged polymer systems can be modeled mesoscopically without the use of explicit charges by forcing a slip between monomers and the surrounding fluid. This model is validated by simulating some surprising predictions made in the literature such as an object with no net charge having a non-zero force when subjected to an electric field, and how the velocity can even be perpendicular to the applied electric field. The thesis can be roughly divided into two topics: using polymer coatings to modulate EOF, and the free solution electrophoresis of polyelectrolytes. While EOF and free solution electrophoresis might seem unrelated it will be shown that the concepts are the same in both cases. In fact while not investigated in this thesis, the mesoscopic simulation methods for electrophoresis could be applied to the modulation of EOF with polymer coatings allowing for the simulation of longer length and time scales or more complex systems such as heterogeneously grafted colloids.
dc.language.isoen
dc.publisherUniversité d'Ottawa / University of Ottawa
dc.subjectelectrophoresis
dc.subjectelectroosmotic flow
dc.subjectmolecular dynamics
dc.subjecthydrodynamic interactions
dc.subjectpolymer
dc.subjectpolyelectrolyte
dc.subjectpolymer adsorption
dc.subjectpolymer brushes
dc.subjectelfse
dc.subjectfree solution electrophoresis
dc.subjectelectrokinetic
dc.subjectelectrohydrodynamics
dc.titleModulating Electro-osmotic Flow with Polymer Coatings
dc.typeThesis
dc.faculty.departmentPhysique / Physics
dc.contributor.supervisorSlater, Gary W.
dc.embargo.termsimmediate
dc.degree.namePhD
dc.degree.leveldoctorate
dc.degree.disciplineSciences / Science
thesis.degree.namePhD
thesis.degree.levelDoctoral
thesis.degree.disciplineSciences / Science
uottawa.departmentPhysique / Physics
CollectionThèses, 2011 - // Theses, 2011 -

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