Date of Award
Master of Science (MS)
Materials Science and Engineering
Dr. Stephen Foulger
Dr. Igor Luzinov
Dr. Kimberly Weirich
Crystalline colloidal arrays (CCAs) are periodic dielectric arrays composed of monodisperse, negatively charged nanoparticles with unique optical characteristics. Poly(styrene-co-propargyl acrylate) (PS-PA) based copolymer nanoparticles synthesized via an emulsion polymerization form the basis of the CCAs in this work. The negatively charged surfaces result in the colloidal nanoparticles self-assembling into a face-centered cubic (fcc) crystal-like structure. The long-range order and spatial periodicity of the array result in a rejection wavelength, characteristic of CCAs, in which a specific wavelength of light is forbidden from propagating throughout the optical system. The CCAs exhibit mechanochromism through a rejection wavelength shift corresponding to a change in the interplanar spacing of the CCAs. The PS-PA particle basis in this work was modified by covalently incorporating organic emitters during synthesis to produce scintillating CCAs. CCA particles were copolymerized with a radioluminescent dye and additional fluorescent dyes to produce emissions across the visible light spectrum, forming three unique sets of CCA particles. Due to the liquid CCA system being sensitive to mechanical stress and ionic impurities, a poly(ethylene glycol) methacrylate (PEGMA) based hydrogel network was photopolymerized in situ with the CCAs to form a more mechanically robust film. By coupling the rejection wavelength with the radioluminescence, the encapsulated CCAs were demonstrated to have tunable emissions. The particular optical characteristics of the fully organic, hydrogel encapsulated, radioluminescent CCAs result in possible future use as potentially less toxic x-ray bioimaging materials.
Mell, Sarah, "Mechanochromic Tunable Emissions of Hydrogel Encapsulated Radioluminescent Crystalline Colloidal Arrays" (2022). All Theses. 3766.