VTechWorks staff will be away for the winter holidays starting Tuesday, December 24, 2024, through Wednesday, January 1, 2025, and will not be replying to requests during this time. Thank you for your patience, and happy holidays!
 

Surfactant Adsorption during Collisions of Colloidal Particles: A Study with Atomic Force Microscopy (AFM)

Simple item page
dc.contributor.authorLokar, William Josephen
dc.contributor.committeechairDucker, William A.en
dc.contributor.committeememberAnderson, Mark R.en
dc.contributor.committeememberYoon, Roe-Hoanen
dc.contributor.committeememberMorris, John R.en
dc.contributor.committeememberEsker, Alan R.en
dc.contributor.departmentChemistryen
dc.date.accessioned2014-03-14T20:14:13Zen
dc.date.adate2004-07-29en
dc.date.available2014-03-14T20:14:13Zen
dc.date.issued2004-07-19en
dc.date.rdate2005-07-29en
dc.date.sdate2004-07-23en
dc.description.abstractThe adsorption of cationic and zwitterionic surfactants is studied in aqueous electrolyte solutions. A Maxwell relation is applied to Atomic Force Microscopy (AFM) data to obtain changes in surfactant adsorption as a function of the separation between two glass surfaces. In addition, self-consistent field theory (SCF) is used to calculate the adsorption profiles and interaction energies when two solid surfaces are brought into close proximity. Addition of surfactant is shown to affect the surface forces when lateral surfactant chain interactions are significant. The surfactant adsorbs and desorbs in response to over-lapping electric double-layers, with the adsorption being affected at larger solid-solid separations when the double-layer force is longer ranged. Furthermore, elimination off the surface charge or net surfactant charge eliminates adsorption with decreased solid-solid separation. The magnitude of the changes in surfactant adsorption at decreased separations is shown to scale with the chain length of the surfactant. Surfactant adsorption exceeds that required to regulate the surface charge according to the constant potential boundary condition in Poisson-Boltzmann theory. An equation of state including short-ranged (contact) tail interactions is proposed to describe both the adsorption of surfactant and the surface forces at small separations, where the double-layers overlap. Furthermore, SCF calculations show confinement-induced phase transitions when the surfactant layers on opposite surfaces merge. These phase transitions lead to further surfactant adsorption and a corresponding attractive force.en
dc.description.degreePh. D.en
dc.identifier.otheretd-07232004-141823en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-07232004-141823/en
dc.identifier.urihttp://hdl.handle.net/10919/28369en
dc.publisherVirginia Techen
dc.relation.haspartDissertation.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectAFMen
dc.subjectself-consistent field theoryen
dc.subjectSurfactanten
dc.subjectproximal adsorptionen
dc.subjectadsorptionen
dc.subjectcharge regulationen
dc.subjectsurface forcesen
dc.titleSurfactant Adsorption during Collisions of Colloidal Particles: A Study with Atomic Force Microscopy (AFM)en
dc.typeDissertationen
thesis.degree.disciplineChemistryen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
Dissertation.pdf
Size:
5.2 MB
Format:
Adobe Portable Document Format
Download

Collections

Doctoral Dissertations