{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/34836"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/34836","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"How water meets a hydrophobic surface: reluctantly and with fluctuations","abstract":"By definition hydrophobic substances hate water. Water placed on a hydrophobic surface will form a drop in order to minimize its contact area. What happens when water is forced into contact with a hydrophobic surface? One theory is that an ultra-thin low-density region forms near the surface. This depleted region would have implications in such diverse areas as colloidal self-assembly, and the boundary conditions of fluid flow. However, the literature still remains divided as to whether or not such a depleted region exists. To investigate the existence of this layer, we have employed three surfacesensitive techniques, time-resolved phase-modulated ellipsometry, surface plasmon resonance, and X-ray reflectivity. Both ellipsometry and X-ray reflectivity provide strong evidence for the low-density layer and illuminate unexpected temporal behavior. Using all three techniques, we found surprising fluctuations at the interface with a non-Gaussian distribution and a single characteristic time on the order of tenths of seconds. This information supports the idea that the boundary fluctuates with something akin to capillary waves. We have also investigated the dependence of the static and dynamic properties of the hydrophobic/water interface on variables such as temperature, contact angle, pH, dissolved gasses, and sample quality, among others, in a hope to discover the root of the controversy in the literature. We found that the depletion layer is highly dependent on temperature, contact angle and sample quality. This dependence might explain some of the discrepancies in the literature as different groups often use hydrophobic surfaces with different properties.","abstract_html":"By definition hydrophobic substances hate water. Water placed on a hydrophobic surface will form a drop in order to minimize its contact area. What happens when water is forced into contact with a hydrophobic surface? One theory is that an ultra-thin low-density region forms near the surface. This depleted region would have implications in such diverse areas as colloidal self-assembly, and the boundary conditions of fluid flow. However, the literature still remains divided as to whether or not such a depleted region exists. To investigate the existence of this layer, we have employed three surfacesensitive techniques, time-resolved phase-modulated ellipsometry, surface plasmon resonance, and X-ray reflectivity. Both ellipsometry and X-ray reflectivity provide strong evidence for the low-density layer and illuminate unexpected temporal behavior. Using all three techniques, we found surprising fluctuations at the interface with a non-Gaussian distribution and a single characteristic time on the order of tenths of seconds. This information supports the idea that the boundary fluctuates with something akin to capillary waves. We have also investigated the dependence of the static and dynamic properties of the hydrophobic/water interface on variables such as temperature, contact angle, pH, dissolved gasses, and sample quality, among others, in a hope to discover the root of the controversy in the literature. We found that the depletion layer is highly dependent on temperature, contact angle and sample quality. This dependence might explain some of the discrepancies in the literature as different groups often use hydrophobic surfaces with different properties.","abstract_has_math":false,"creators":["Poynor Torigoe, Adele Nichole"],"institution":null,"degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Granick, Steve"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012-10-26T23:11:09Z","date_published":"2012-10-26T23:11:09Z","updated_at":"2026-07-22T22:25:31Z","subjects":["Water/Hydrophobic Interface","X-Ray Reflectivity","Surface Plasmon Resonance"],"languages":["en"],"rights":["©2006 Adele Nichole Poyner Torigoe"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["5641604"],"render_values":[{"text":"5641604","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/34836","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Granick, Steve"]},{"key":"dc:creator","label":"Author","values":["Poynor Torigoe, Adele Nichole"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2012-10-26T23:11:09Z","10000-01-01","2006-10"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation / Thesis","text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Water/Hydrophobic Interface","X-Ray Reflectivity","Surface Plasmon Resonance"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["©2006 Adele Nichole Poyner Torigoe"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["5641604","http://hdl.handle.net/2142/34836"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["By definition hydrophobic substances hate water. Water placed on a hydrophobic surface will form a drop in order to minimize its contact area. What happens when water is forced into contact with a hydrophobic surface? One theory is that an ultra-thin low-density region forms near the surface. This depleted region would have implications in such diverse areas as colloidal self-assembly, and the boundary conditions of fluid flow. However, the literature still remains divided as to whether or not such a depleted region exists. To investigate the existence of this layer, we have employed three surfacesensitive techniques, time-resolved phase-modulated ellipsometry, surface plasmon resonance, and X-ray reflectivity. Both ellipsometry and X-ray reflectivity provide strong evidence for the low-density layer and illuminate unexpected temporal behavior. Using all three techniques, we found surprising fluctuations at the interface with a non-Gaussian distribution and a single characteristic time on the order of tenths of seconds. This information supports the idea that the boundary fluctuates with something akin to capillary waves. We have also investigated the dependence of the static and dynamic properties of the hydrophobic/water interface on variables such as temperature, contact angle, pH, dissolved gasses, and sample quality, among others, in a hope to discover the root of the controversy in the literature. We found that the depletion layer is highly dependent on temperature, contact angle and sample quality. This dependence might explain some of the discrepancies in the literature as different groups often use hydrophobic surfaces with different properties.","Submitted by Meng Tao (mengtao2@illinois.edu) on 2012-10-26T23:11:09Z No. of bitstreams: 1 Poynor_Torigoe_Adele.pdf: 1952309 bytes, checksum: e34d29ee136f41cdfc85c9fa2c455ea1 (MD5)","Made available in DSpace on 2012-10-26T23:11:09Z (GMT). No. of bitstreams: 1 Poynor_Torigoe_Adele.pdf: 1952309 bytes, checksum: e34d29ee136f41cdfc85c9fa2c455ea1 (MD5) Previous issue date: 2006-10","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Meng Tao (mengtao2@illinois.edu) on 2012-10-26T23:11:10Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:11:15-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Post 1923. No authorization form.","Post 1923. No authorization form.","U of I Only"]},{"key":"dc:title","label":"Title","values":["How water meets a hydrophobic surface: reluctantly and with fluctuations"]}]}],"canonical_facts":{"dc:contributor":["Granick, Steve"],"dc:creator":["Poynor Torigoe, Adele Nichole"],"dc:date":["2012-10-26T23:11:09Z","10000-01-01","2006-10"],"dc:description":["By definition hydrophobic substances hate water. Water placed on a hydrophobic surface will form a drop in order to minimize its contact area. What happens when water is forced into contact with a hydrophobic surface? One theory is that an ultra-thin low-density region forms near the surface. This depleted region would have implications in such diverse areas as colloidal self-assembly, and the boundary conditions of fluid flow. However, the literature still remains divided as to whether or not such a depleted region exists. To investigate the existence of this layer, we have employed three surfacesensitive techniques, time-resolved phase-modulated ellipsometry, surface plasmon resonance, and X-ray reflectivity. Both ellipsometry and X-ray reflectivity provide strong evidence for the low-density layer and illuminate unexpected temporal behavior. Using all three techniques, we found surprising fluctuations at the interface with a non-Gaussian distribution and a single characteristic time on the order of tenths of seconds. This information supports the idea that the boundary fluctuates with something akin to capillary waves. We have also investigated the dependence of the static and dynamic properties of the hydrophobic/water interface on variables such as temperature, contact angle, pH, dissolved gasses, and sample quality, among others, in a hope to discover the root of the controversy in the literature. We found that the depletion layer is highly dependent on temperature, contact angle and sample quality. This dependence might explain some of the discrepancies in the literature as different groups often use hydrophobic surfaces with different properties.","Submitted by Meng Tao (mengtao2@illinois.edu) on 2012-10-26T23:11:09Z No. of bitstreams: 1 Poynor_Torigoe_Adele.pdf: 1952309 bytes, checksum: e34d29ee136f41cdfc85c9fa2c455ea1 (MD5)","Made available in DSpace on 2012-10-26T23:11:09Z (GMT). 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No authorization form.","U of I Only"],"dc:identifier":["5641604","http://hdl.handle.net/2142/34836"],"dc:language":["en"],"dc:rights":["©2006 Adele Nichole Poyner Torigoe"],"dc:subject":["Water/Hydrophobic Interface","X-Ray Reflectivity","Surface Plasmon Resonance"],"dc:title":["How water meets a hydrophobic surface: reluctantly and with fluctuations"],"dc:type":["Dissertation / Thesis","text"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."]},"updated_at":"2026-07-22T22:25:31Z"}