Research
Our group is actively involved in multiple areas of research. Below is a brief description of each area.
Conjugated polymer (CP) Grafted from Cellulose Nanocrystals (CNC)
We have been working to demonstrate and understand the synthesis of conjugated polymer (CP) grafted from cellulose nanocrystal (CNC) composite materials. We have demonstrated the synthesis of poly (2-ethynylene-9,9-dihexyl fluorene) (PEF) and poly (3-hexylthiophene) (P3HT) grafted CNC composites and confirmed their respective successes via FTIR, XPS, UV-Vis, and MALDI-ToF analyses. We plan on employing grafted CP CNC composite materials as active layer materials in OLEDs and sensors. We strive to 1) develop deeper understandings of the chemistries occurring through these graft processes, 2) demonstrate the capabilities of these materials as electronic device active layers, and 3) pursue more applications in the field of renewable electronics.
Synthesis and Photo-Physical Characterization of Carborane-Containing Semiconducting Polymers
Incorporation of o-carborane into the backbone of poly(dihexylfluorene)s drastically effects emission properties due to an intramolecular charge transfer state (ICT) that forms between the fluorene and carborane moieties in the polymer backbone. The formed ICT state is emissive and experiences solvatochromism, as well as aggregated induced emission enhancement (AIEE). Such polymers exhibit duel emissions from both the ICT state and the conjugated fluorene local excited state (LES). The novel synthesis of poly((bisthienyl) carborane) (homopolymer) and poly((bisthienyl)carborane-co-thiophene) (copolymer) allows us to understand the exited state dynamics of soluble strong donor-carborane junctions in conjugated polymer systems, and also gives evidence for use of carborane as a spin-coupling moiety for triplet sensitization applications. The main characteristics of these polymers enables them for future use in cancer therapy studies or photodynamic therapies, in that they are polar and soluble in DMSO, a biologically compatible solvent, absorb in the visible light spectrum, and can facilitate long lived triplet states.
Benzimidazole-Containing Conjugated Donor-Acceptor Polymers
Conjugated polymers continue to enjoy considerable interest owing to their marriage of semiconducting properties with inherent polymeric qualities (solution processability, mechanical flexibility, lightweight, etc.). Due to their semiconducting nature, these materials find applications in numerous electronic devices (light-emitting diodes, photovoltaic cells, thin-film transistors, electrochromic cells, etc.). However, conjugated polymers suffer from numerous drawbacks, limiting their commercial scalability. Namely; ill-defined morphologies obfuscating charge-transport mechanisms, high batch-to-batch variability, and low oxidative stability. Additionally, unlike inorganic systems, manipulating charge-carrier type and mobility after polymerization remains a major challenge for these materials. Our, and others’, work with imidazole-containing conjugated polymers suggest a route to tune frontier molecular orbitals post-polymerization through controlling the charge state of the polymer backbone.
Three-Dimensional Woodpile Nanostructures to Achieve High-Sensitivity Enzymatic Glucose Biosensors
Fabrication of detection elements with ultra-high surface area is essential for improving the sensitivity of analyte detection. In collaboration with the Watkins group, we use nanoimprint lithography (NIL) as a direct patterning technique to fabricate high-performance nanoelectrode arrays for biosensor application over relatively large areas. The fabrication approach, which employs a nanoparticle based ink, enables the direct, high throughput patterning of nanostructures and is scalable, integratable and low cost.
Stimuli Responsive and Self-Exfoliating Films for Protective Layer Against Chemical Warfare Agents
The overall objective of this project is to develop a protective polymeric layer that effectively neutralizes and removes chemical warfare agent (CWA) upon contact. Our approach is to synthesize acid-degradable crosslinked hydrogels containing a compound that is reactive to various CWAs and will undergo a self-exfoliation process, or shedding, upon activation during exposure. The mechanism of this exfoliation is triggered by acidic byproducts of CWA neutralization.
Nanocellulose Aerogels for CO2 Capture
The progressively increasing atmospheric CO2 concentration has caused enough alarm to spur research focused on reducing global CO2 output. The overall goal of this research project is to create a new technology platform that can cheaply and effectively remove CO from industrial waste streams (i.e. smokestacks). To accomplish this goal, we propose an interdisciplinary approach encompassing expertise in the fields of polymer chemistry, material science, and engineering, as outlined in the four specific objectives below. The core of the proposed materials is nanocellulose, an abundant, but currently underutilized biomass. Our project represents the creation of an entirely new process to produce value-added products, namely nanocellulose aerogels for CO2 capture. When combined with simple amino acids these aerogel materials have extraordinary CO2 capture capacity. This project will allow us to make, test and begin to examine commercial feasibility of these new materials.
