Functional surface nanodroplets for sensitive chemical analysis and nanomaterials synthesis

• Author / Creator

  Wei, Zixiang

• Surface nanodroplets are nano-scale droplets immobilized on a solid surface with an immiscible liquid environment. These droplets possess a large surface area to volume ratio and some desirable properties such as a long lifetime and excellent stability, compared to the bulk droplets. Surface nanodroplets can be formed in a simple and highly controllable process of solvent exchange. Thus, surface nanodroplets have the potential to be applied in lab-on-chip deceive design, highly sensitive chemical sensing, micro-reactors, high-resolution imaging, catalytic reaction and others. The novelty of our works is that we applied the advantages of accelerated mass transfer and reaction rate of the surface nanodroplet in fast acid mixture detection and controllable surface-bound materials synthesis.\\
  
  This thesis reports acid detection and nanomaterials synthesis by using functional surface nanodroplets. The surface nanodroplets containing halochromic chemical compounds are formed by solvent exchange. A colorimetric reaction takes place in the droplets by extracting acidic analyte from the bulk. The time scale of the color change depends on the droplet size, interfacial properties and the dissociation constant of the analyte. The decoloration time is specific to the acid type, giving the possibility to distinguish the multi-component mixtures. Compared to other acid detectors, surface nanodroplets give a faster and more visualized result based on the color change and show potential in instrument-free detection. Furthermore, a partition shifting down of the analyte is found by the coupled extraction and reaction process of the surface nanodroplet. A higher sensitivity of the colorimetric reaction in droplets is obtained compared to the bulk system. The coupled nanoextraction and chemical reaction have been theoretically investigated and show good agreement with the experimental results. Finally, the surface nanodroplets are used as the template and nucleation site to fabricate the surface-bound materials from the biphasic reaction. Surface nanodroplets enhanced the biphasic reaction, reducing the need of catalyst and additive chemicals, compared to the reaction in bulk. Micro- or nano-structures of metal and metal oxides are fabricated, which can be applied in photo-catalytic degradation and surface enhancement Raman scattering.

• Subjects / Keywords

  • Interface
  • nanodroplets
  • chemical analysis
  • material synthesis

• Graduation date

  Spring 2022

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-5krm-pk38

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.