Exploiting Maximum Capillary Pressure and Detachment Energy Synergy for 3D-Printable High Internal Phase Emulsions with Ultra-low Loadings of Water-Wetting Carbon Dots
Date
2024-04-02
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Abstract
High Internal Phase Emulsions (HIPEs), with internal phase volume fractions exceeding 0.74, hold potential for diverse applications. Nonetheless, their broader adoption is constrained by limitations, including the need for high concentrations of stabilizers and the ability to fine-tune their morphology. This thesis evaluates the capability of two fully water-wetting sub-10 nm asphaltene-derived carbon dots — asphaltene-derived carbon dots 1 (ACD1) and asphaltene-derived carbon dots 2 (ACD2) — for stabilizing oil-in-water (o/w) HIPE. A universal route is introduced to generate o/w HIPEs with ultra-low loading of water-wetting solid stabilizers by exploiting the synergy of high maximum capillary pressure to resist the thinning of liquid films and particle detachment energy. The HIPE formation involves a 2-minute single-step homogenization of ACDs, water, and dodecane. HIPE was generated with a minimal particle loading of 0.025wt% ACD1, capable of emulsifying 0.82 of oil volume fraction. To probe the link between the evolving microstructure and rheological properties, laser scanning confocal microscopy (LSCM), rheometer, and confocal-rheology (LSCM in conjunction with dynamic oscillatory amplitude sweep) were utilized, testing HIPE thixotropy and creep recovery. A correlation between the HIPE microstructure and rheological properties with the emulsion stabilization mechanisms has been established. The result is a HIPE with spherical dispersed droplets, superior thixotropy, shear-thinning behavior, excellent creep recovery, complete structural recovery, and storage stability of more than 6 months, achieved with just 0.075wt% ACD1 loading. Taking advantage of these properties, finely detailed 3D structures have been successfully printed using an ultra-low loading of 0.075wt% ACD1-stabilized HIPE in an extrusion-based 3D printing method at a low extrusion pressure of 4kPa with a nozzle diameter of just 0.400 mm. This addresses the challenges in HIPE 3D printing, like high extrusion pressures and the need for large nozzle sizes or additional chemicals, thereby broadening the potential applications of HIPEs in 3D printing technologies.
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Keywords
Asphaltene-derived carbon dots, high internal phase emulsions, extrusion-based 3D printing
Citation
Karhana, G. (2024). Exploiting maximum capillary pressure and detachment energy synergy for 3D-printable high internal phase emulsions with ultra-low loadings of water-wetting carbon dots (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.