Add a Pinch of Salt: Effects of Additives for the Development of New Materials
- Author(s): Mak, Wai Han
- Advisor(s): Kaner, Richard B
- et al.
Something as simple as adding a pinch of salt can make or break a dish. The same can be said for the process of materials development. The field of chemistry and material science is ever expanding and, with it, a call to develop new materials. Challenges include improving existing methods for production and devising new ways to design materials for particular functions. One way to do this is through the use of chemical additives. Adding even a small amount of additives can enhance material properties, aid in kinetics of chemical reactions, and act as templates in the solid state.The goal of this thesis is to explore the role of additives in materials science through the lens of a chemist. This can be summarized through three parts: (1) A novel top-down method for the exfoliation of two-dimensional (2D) layered materials was developed using compressible flow. Graphite, hexagonal boron nitride, and molybdenum disulfide were used as representative 2D layered materials. Our process takes advantage of supersonic flow and weak van der Waals forces to mechanically exfoliate 2D materials in seconds. Exfoliated few-layered hexagonal boron nitride produced by our method was used as an additive in polyethylene terephthalate (PET) resulting in an increase in modulus and a decrease in the oxygen permeation rate compared to PET by itself. (2) Additives can be used to speed up chemical reactions such as for the polymerization of aniline. The addition of oligoanilines can speed up aniline polymerization, with the small molecule acting as a catalyst. Quantitative rate constants were determined using electrochemical polymerization of aniline by adding various oligomers to study the kinetics and growth mechanism of polyaniline. (3) Carbon additives can be utilized as “templates” in dodecaboride solid solutions to direct surface morphology. The single-phase metal dodecaboride solid solutions, Zr0.5Y0.5B12 and Zr0.5U0.5B12, were prepared using solid solution alloying. Compared to their parent phases, ZrB12 and YB12, Zr0.5Y0.5B12 and Zr0.5U0.5B12, they have enhanced hardnesses. The addition of carbon into the zirconium–yttrium dodecaboride system causes rapid nucleation of grains causing changes in surface morphology.