Towards Colloidal Self-Assembly for Functional Materials

Abstract

Nanostructuring has led to materials with novel and improved materials properties driving innovation across fields as varied as transportation, computing, energy and biotechnology. However, the benefits of nanostructured material have not widely been extended into large-scale, three-dimensional applications as deterministic pattern techniques have proven too expensive for devices outside of high value products. This thesis explores how colloidal self-assembly can be used to form macroscopic functional materials with short-range order for electronic, photonic and electrochemical applications at scale.

DNA-functionalized nanoparticles are versatile models for exploring colloidal self-assembly due to the highly specific, tunable and thermally reversible binding between DNA strands. Gold nanoparticles coated with DNA were used to investigate the temperature-dependent interaction potentials and the gel formation in DNA-colloidal systems. The electronic conductivity and the plasmonic response of the DNA-gold gels were studied to explore their applicability as porous electrodes and SERS substrates, respectively. Subsequently, silica nanoparticles were assembled into nanostructures that preferentially scatter blue light using both DNA and polymer-colloid interactions. Finally, rod-sphere structures made from DNA-coated gold nanoparticles and viruses were explored, demonstrating how high-aspect ratio building blocks can create composite structures with increased porosity. The gold-virus gel structures inspired the design and assembly of a silicon-carbon nanotube composite material using covalent bonds that shows promise for high energy density anodes.