{"id":{"repo_id":"cambridge","oai_identifier":"oai:www.repository.cam.ac.uk:1810/381615"},"canonical_url":"https://search.dev.ndltd.org/etd/cambridge/oai:www.repository.cam.ac.uk:1810/381615","repository":{"repo_id":"cambridge","name":"Cambridge University","base_url":"https://api.repository.cam.ac.uk/server/oai/request"},"display":{"title":"Ethoxylated amine surfactants as model additives for engine friction reduction","abstract":"The exact mechanism by which organic friction modifiers (OFMs) adsorb onto metallic surfaces and reduce friction remains debated. To optimise the use of these compounds, a precise understanding of their mechanism is essential. This knowledge will drive the development of next-generation additives, which could significantly extend engine lifespans and reduce fuel emissions. Hindered tertiary amine surfactants are promising candidates as OFMs. In this thesis, the self-assembly and adsorption behaviour of an industrially relevant OFM, 2,2’-(Octadecylazanediyl)diethanol (E1812), is investigated both in bulk dodecane and at the hematite/dodecane interface, to shed light on its friction-reducing mechanism. Chapter 3 examines the self-assembly of E1812 in dodecane through pendant drop tensiometry and small angle neutron scattering (SANS). The surfactant was found to form spherical aggregates with a radius of ∼ 11 Å at 25 °C, and its behaviour was influenced by solvent changes and dopant addition. As explored by SANS in Chapter 4, addition of 2.5−20 : 1 molar ratios of acetic acid (AcOH) to E1812 solutions caused the formation of worm-like micelles (WLMs) that were both concentration- and time-dependent. These were hypothesised to lack a well-defined global energy minimum, due to the hydrogen-bonding interaction of E1812 headgroups, AcOH, and native dissolved water, as well as the formation of trialkylammonium acetate salt. Chapter 5 investigates the adsorption of E1812 at the hematite/dodecane interface under static conditions, by neutron reflectometry (NR). The surfactant exhibited multilayer adsorption, as described by Freundlich isotherms, with the onset occurring above a concentration of 2.5 mM. E1812 formed strongly-bound protective films with a thickness of ∼ 20 Å , effectively screening the interface from water and competing with oleic acid (OA) for surface adsorption. As discussed in Chapter 6, the addition of AcOH largely induced off-specular scattering in NR studies, suggesting surface-correlated roughness likely linked to WLM formation in the bulk. It is hypothesised that E1812-AcOH mixtures adsorb as double-layer structures, with E1812 strongly bound to the surface and the laterally correlated, AcOH-containing species weakly adsorbed. To investigate conditions relevant to engine operation, Chapter 7 explores the adsorption of E1812 at the hematite/dodecane interface under shear, by NR. E1812 films remained stable under applied shear rates of 7.9×10³ s⁻¹, presenting a marginally increased thickness of ∼ 24 Å . The surfactant effectively shielded the interface from water adsorption under the same dynamic conditions and, under shear of 6.6×10³ s⁻¹, its co-adsorption with OA indicated that ΔHads,OA ≤ ΔHads,E1812 at the interface under study. Additionally, E1812 protected the interface from direct AcOH adsorption at a shear rate of 7.9×10³ s⁻¹, where off-specular scattering was removed. As discussed in Chapter 8, mini-traction machine (MTM) testing showed that E1812 enhanced the boundary lubrication of pure dodecane, particularly when mixed with AcOH, highlighting the role of WLMs in improving friction performance.","abstract_html":"The exact mechanism by which organic friction modifiers (OFMs) adsorb onto metallic surfaces and reduce friction remains debated. To optimise the use of these compounds, a precise understanding of their mechanism is essential. This knowledge will drive the development of next-generation additives, which could significantly extend engine lifespans and reduce fuel emissions. Hindered tertiary amine surfactants are promising candidates as OFMs. In this thesis, the self-assembly and adsorption behaviour of an industrially relevant OFM, 2,2’-(Octadecylazanediyl)diethanol (E1812), is investigated both in bulk dodecane and at the hematite/dodecane interface, to shed light on its friction-reducing mechanism. Chapter 3 examines the self-assembly of E1812 in dodecane through pendant drop tensiometry and small angle neutron scattering (SANS). The surfactant was found to form spherical aggregates with a radius of ∼ 11 Å at 25 °C, and its behaviour was influenced by solvent changes and dopant addition. As explored by SANS in Chapter 4, addition of 2.5−20 : 1 molar ratios of acetic acid (AcOH) to E1812 solutions caused the formation of worm-like micelles (WLMs) that were both concentration- and time-dependent. These were hypothesised to lack a well-defined global energy minimum, due to the hydrogen-bonding interaction of E1812 headgroups, AcOH, and native dissolved water, as well as the formation of trialkylammonium acetate salt. Chapter 5 investigates the adsorption of E1812 at the hematite/dodecane interface under static conditions, by neutron reflectometry (NR). The surfactant exhibited multilayer adsorption, as described by Freundlich isotherms, with the onset occurring above a concentration of 2.5 mM. E1812 formed strongly-bound protective films with a thickness of ∼ 20 Å , effectively screening the interface from water and competing with oleic acid (OA) for surface adsorption. As discussed in Chapter 6, the addition of AcOH largely induced off-specular scattering in NR studies, suggesting surface-correlated roughness likely linked to WLM formation in the bulk. It is hypothesised that E1812-AcOH mixtures adsorb as double-layer structures, with E1812 strongly bound to the surface and the laterally correlated, AcOH-containing species weakly adsorbed. To investigate conditions relevant to engine operation, Chapter 7 explores the adsorption of E1812 at the hematite/dodecane interface under shear, by NR. E1812 films remained stable under applied shear rates of 7.9×10³ s⁻¹, presenting a marginally increased thickness of ∼ 24 Å . The surfactant effectively shielded the interface from water adsorption under the same dynamic conditions and, under shear of 6.6×10³ s⁻¹, its co-adsorption with OA indicated that ΔHads,OA ≤ ΔHads,E1812 at the interface under study. Additionally, E1812 protected the interface from direct AcOH adsorption at a shear rate of 7.9×10³ s⁻¹, where off-specular scattering was removed. As discussed in Chapter 8, mini-traction machine (MTM) testing showed that E1812 enhanced the boundary lubrication of pure dodecane, particularly when mixed with AcOH, highlighting the role of WLMs in improving friction performance.","abstract_has_math":false,"creators":["Boggio-Robutti, Beatrice"],"institution":"University of Cambridge","degree_name":"Doctor of Philosophy (PhD)","degree_level":"Doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Routh, Alexander"],"committee_chairs":[],"committee_members":[],"year":2024,"date_issued":"2024-09-30","date_published":"2024-09-30","updated_at":"2026-07-22T22:24:01Z","subjects":["Adsorption","Lubrication","Neutron Reflectometry","Neutron Scattering","Organic Friction Modifiers","Tribology"],"languages":["eng"],"rights":[],"rights_urls":["https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/cf6e08a5-2434-48ce-9e28-a587480b1b09/download","http://purl.org/NET/rdflicense/allrightsreserved"],"identifier_entries":[]},"links":{"outbound_url":"https://doi.org/10.17863/CAM.116741","outbound_label":"DOI","outbound_source":"dc:identifier.doi"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Routh, Alexander"]},{"key":"dc:contributor.sponsor","label":"Sponsor","values":["UKRI grant references EP/T517847/1 and 2403019"]},{"key":"dc:creator","label":"Author","values":["Boggio-Robutti, Beatrice"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.issued","label":"Date","values":["2024-09-30"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Cambridge"]},{"key":"dc:relation.isreferencedby.uri","label":"Dc Relation Isreferencedby URI","values":["https://www.repository.cam.ac.uk/handle/1810/381615"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["Doctor of Philosophy (PhD)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Adsorption","Lubrication","Neutron Reflectometry","Neutron Scattering","Organic Friction Modifiers","Tribology"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/cf6e08a5-2434-48ce-9e28-a587480b1b09/download","http://purl.org/NET/rdflicense/allrightsreserved"]},{"key":"dc:rights.embargodate","label":"Dc Rights Embargodate","values":["2026-03-18"]},{"key":"dc:rights.embargotype","label":"Dc Rights Embargotype","values":["embargo"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.doi","label":"DOI","values":["https://doi.org/10.17863/CAM.116741"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/c2515de9-a9df-4c2b-9a04-59578c2d3f5c/download"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The exact mechanism by which organic friction modifiers (OFMs) adsorb onto metallic surfaces and reduce friction remains debated. To optimise the use of these compounds, a precise understanding of their mechanism is essential. This knowledge will drive the development of next-generation additives, which could significantly extend engine lifespans and reduce fuel emissions. Hindered tertiary amine surfactants are promising candidates as OFMs. In this thesis, the self-assembly and adsorption behaviour of an industrially relevant OFM, 2,2’-(Octadecylazanediyl)diethanol (E1812), is investigated both in bulk dodecane and at the hematite/dodecane interface, to shed light on its friction-reducing mechanism. Chapter 3 examines the self-assembly of E1812 in dodecane through pendant drop tensiometry and small angle neutron scattering (SANS). The surfactant was found to form spherical aggregates with a radius of ∼ 11 Å at 25 °C, and its behaviour was influenced by solvent changes and dopant addition. As explored by SANS in Chapter 4, addition of 2.5−20 : 1 molar ratios of acetic acid (AcOH) to E1812 solutions caused the formation of worm-like micelles (WLMs) that were both concentration- and time-dependent. These were hypothesised to lack a well-defined global energy minimum, due to the hydrogen-bonding interaction of E1812 headgroups, AcOH, and native dissolved water, as well as the formation of trialkylammonium acetate salt. Chapter 5 investigates the adsorption of E1812 at the hematite/dodecane interface under static conditions, by neutron reflectometry (NR). The surfactant exhibited multilayer adsorption, as described by Freundlich isotherms, with the onset occurring above a concentration of 2.5 mM. E1812 formed strongly-bound protective films with a thickness of ∼ 20 Å , effectively screening the interface from water and competing with oleic acid (OA) for surface adsorption. As discussed in Chapter 6, the addition of AcOH largely induced off-specular scattering in NR studies, suggesting surface-correlated roughness likely linked to WLM formation in the bulk. It is hypothesised that E1812-AcOH mixtures adsorb as double-layer structures, with E1812 strongly bound to the surface and the laterally correlated, AcOH-containing species weakly adsorbed. To investigate conditions relevant to engine operation, Chapter 7 explores the adsorption of E1812 at the hematite/dodecane interface under shear, by NR. E1812 films remained stable under applied shear rates of 7.9×10³ s⁻¹, presenting a marginally increased thickness of ∼ 24 Å . The surfactant effectively shielded the interface from water adsorption under the same dynamic conditions and, under shear of 6.6×10³ s⁻¹, its co-adsorption with OA indicated that ΔHads,OA ≤ ΔHads,E1812 at the interface under study. Additionally, E1812 protected the interface from direct AcOH adsorption at a shear rate of 7.9×10³ s⁻¹, where off-specular scattering was removed. As discussed in Chapter 8, mini-traction machine (MTM) testing showed that E1812 enhanced the boundary lubrication of pure dodecane, particularly when mixed with AcOH, highlighting the role of WLMs in improving friction performance."]},{"key":"dc:format.checksum.md5","label":"Dc Format Checksum Md5","values":["6b968080fe58c81f68ec8b4b53b8f9c0","87eda9de84448d1f82354d60eee3eb5f"]},{"key":"dc:title","label":"Title","values":["Ethoxylated amine surfactants as model additives for engine friction reduction"]}]}],"canonical_facts":{"dc:contributor.advisor":["Routh, Alexander"],"dc:contributor.sponsor":["UKRI grant references EP/T517847/1 and 2403019"],"dc:creator":["Boggio-Robutti, Beatrice"],"dc:date.issued":["2024-09-30"],"dc:description.abstract":["The exact mechanism by which organic friction modifiers (OFMs) adsorb onto metallic surfaces and reduce friction remains debated. To optimise the use of these compounds, a precise understanding of their mechanism is essential. This knowledge will drive the development of next-generation additives, which could significantly extend engine lifespans and reduce fuel emissions. Hindered tertiary amine surfactants are promising candidates as OFMs. In this thesis, the self-assembly and adsorption behaviour of an industrially relevant OFM, 2,2’-(Octadecylazanediyl)diethanol (E1812), is investigated both in bulk dodecane and at the hematite/dodecane interface, to shed light on its friction-reducing mechanism. Chapter 3 examines the self-assembly of E1812 in dodecane through pendant drop tensiometry and small angle neutron scattering (SANS). The surfactant was found to form spherical aggregates with a radius of ∼ 11 Å at 25 °C, and its behaviour was influenced by solvent changes and dopant addition. As explored by SANS in Chapter 4, addition of 2.5−20 : 1 molar ratios of acetic acid (AcOH) to E1812 solutions caused the formation of worm-like micelles (WLMs) that were both concentration- and time-dependent. These were hypothesised to lack a well-defined global energy minimum, due to the hydrogen-bonding interaction of E1812 headgroups, AcOH, and native dissolved water, as well as the formation of trialkylammonium acetate salt. Chapter 5 investigates the adsorption of E1812 at the hematite/dodecane interface under static conditions, by neutron reflectometry (NR). The surfactant exhibited multilayer adsorption, as described by Freundlich isotherms, with the onset occurring above a concentration of 2.5 mM. E1812 formed strongly-bound protective films with a thickness of ∼ 20 Å , effectively screening the interface from water and competing with oleic acid (OA) for surface adsorption. As discussed in Chapter 6, the addition of AcOH largely induced off-specular scattering in NR studies, suggesting surface-correlated roughness likely linked to WLM formation in the bulk. It is hypothesised that E1812-AcOH mixtures adsorb as double-layer structures, with E1812 strongly bound to the surface and the laterally correlated, AcOH-containing species weakly adsorbed. To investigate conditions relevant to engine operation, Chapter 7 explores the adsorption of E1812 at the hematite/dodecane interface under shear, by NR. E1812 films remained stable under applied shear rates of 7.9×10³ s⁻¹, presenting a marginally increased thickness of ∼ 24 Å . The surfactant effectively shielded the interface from water adsorption under the same dynamic conditions and, under shear of 6.6×10³ s⁻¹, its co-adsorption with OA indicated that ΔHads,OA ≤ ΔHads,E1812 at the interface under study. Additionally, E1812 protected the interface from direct AcOH adsorption at a shear rate of 7.9×10³ s⁻¹, where off-specular scattering was removed. 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