Alice M. Savage

Synthesis and characterization of anion-exchange membranes based on hydrogenated poly(norbornene)

Trimethylammonium-containing (TMA) polynorbornene is synthesized via ring-opening metathesis polymerization for study as an anion exchange membrane (AEM) in solid state alkaline fuel cells. The AEMs in this work are designed to incorporate flexible tethers between the TMA and polymer backbone, methyl groups at the β position, and to be semicrystalline, with the goals of high OH− conductivity, good electrochemical stability in high pH environments, and robust mechanical properties when in the membrane form. The resulting materials are found to have high conductivities, but are mechanically weak due to an overall lack of crystalline domains. Electrochemical stability appears dependent on the environment in which lifetime is measured, suggesting that the hydration state of the polymer has a substantial influence on the result.

Macroscopic Alignment of Silver Nanoplates in an Adaptable Dichroic Polarizer

Morphological control to precisely tailor the energy absorption bands of plasmonic particles is improving constantly, with efforts to improve the monodispersity of the designed particles leading to sharper plasmonic features in controlled spectral regions. Transitioning these highly tailored plasmonic additives into a robust polymer composite platforms while retaining their specified plasmonic features has proven challenging, with the elevated temperatures and mechanical forces involved in composite manufacturing resulting in particle agglomeration and morphology alterations. In this work, thermally stable protecting layers are developed onto tailored silver nanoplate (Ag-NPL) plasmonic additives to facilitate their survivable processing at elevated temperature. The produced coatings allow for their implementation in a facile, low-cost method to produce uniform dichroic optical polarizers based on the protected Ag-NPLs in a polymer matrix. Nanocomposites are obtained through an extrusion and injection molding process, which is shown to induce alignment of anisotropic particles based on sheer forces. As the optical position of the resonances is dependent on the morphology of the additive, and unlike other methods where the anisotropy in the NP is induced in situ, our method can be easily adapted to varying optical regimes by modifying the size and shape of the initial additive. Furthermore, the method presented in this work forgoes the need for a polymer stretching alignment mechanism which enables the ability to use various types of anisotropic particles with visible and near-infrared operating regimes.

Plasmonic gold nanostars as optical nano-additives for injection molded polymer composites

Nanoscale engineering of noble metal particles has provided numerous material configurations to selectively confine and manipulate light across the electromagnetic spectrum. Transitioning these materials to a composite form while maintaining the desired resonance properties has proven challenging. In this work, the successful integration of plasmon-focusing gold nanostars (GNSs) into polymer nanocomposites (PNCs) is demonstrated. Tailored GNSs are produced with over a 90% yield and methods to control the branching structures are shown. A protective silica capping shell is employed on the nanomaterials to facilitate survivability in the high temperate/high shear processing parameters to create optically-tuned injection molded PNCs. The developed GNS PNCs possess dichroic scattering and absorption behavior, opening up potential applications in the fields of holographic imaging, optical filtering and photovoltaics.