Microfluidics Meets Nanomaterials Synthesis
Open Access
- Author:
- Lu, Mengqian
- Graduate Program:
- Engineering Science and Mechanics
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- March 05, 2014
- Committee Members:
- Jun Huang, Dissertation Advisor/Co-Advisor
Akhlesh Lakhtakia, Committee Member
Jian Xu, Committee Member
Iam Choon Khoo, Committee Member - Keywords:
- nanomaterials synthesis
microfluidic reactor
DNA-polymer nanocomplexes (polyplexes) - Abstract:
- Nanomaterials and their applications have attracted great research interest in recent years. As the sizes of materials decrease to sub-micrometers, the intrinsic properties of the nanomaterials become different from those of bulk materials. Since the intrinsic properties of nanomaterials are strongly influenced by the elemental composition, size and shape, it is of great importance to synthesize nanomaterials with controlled reaction conditions (e.g., pressure, temperature, reagent ratio) to achieve high uniformity and reproducibility of the synthesized nanomaterials. It is difficult to achieve homogeneous chemical environment during the conventional chemical synthesis process, where the reagents are mixed at millimeter- or centimeter-scale. Microfluidic reactors, which confine the reaction volume to nanoliter or even picoliter size, have attracted a lot of research interests due to their potential in high-quality nanomaterials synthesis. However, broad distributions of the size and composition of the synthesized nanomaterials still exist within simple microfluidic reactors. In this dissertation, the hypothesis is that diffusion-limit reactions occur within microfluidic reactors, and by improving the mixing efficiency within microfluidic reactors, the quality (e.g., uniformity and performance) of the synthesized nanomaterials can be improved significantly. Furthermore, by controlling the mixing process precisely, the properties (e.g., shape and size) of the synthesized nanomaterials can be finely tuned. To prove this hypothesis, I used microfluidic reactors with designs to improve mixing performance to synthesize polymer-DNA nanocomplexes (polyplexes) and organic-metal hybrid nanomaterials. One design is the acoustic-assisted bubble based microfluidic reactor, which can enhance the mixing performance by random advection within the whole microfluidic channel. The other design used here is the acoustic-assisted three-dimensional hydrodynamic focusing reactor, which can enhance mixing by reducing the diffusion distance. Both of the designs can synthesize polyplexes with improved uniformity and biological performance compared to bulk mixing samples. Moreover, the three-dimensional hydrodynamic focusing method also shows ability to control over the local chemical ratio within the reaction zone. This property is demonstrated by the shape tunable synthesis of organic-metal hybrid nanomaterials.