Date of Award
5-12-2024
Degree Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Chemistry
Advisor(s)
Rachel Steinhardt
Subject Categories
Chemistry | Physical Sciences and Mathematics
Abstract
Chapter 2: Surface Functionalization of Thermally-Expandable Microspheres with Gold Nanoparticles The advancement of methods for controlling motion on a variety of scales is significant in order to develop finely tuned next-generation devices. Here, we’ve created a micron-scale actuator system triggered via photothermal activation and capable of powering macro-scale movement in an elastomer matrix. This system fundamentally relies on thermally-expandable microspheres (TEMs) – a core-shell complex containing a polymeric shell and liquid core that expands dramatically upon heating. To improve the ability of TEMs as soft-actuators controlled via light, we grafted a secondary silicate-silane copolymer shell to attach gold nanoparticles. The gold nanoparticle coating serves as a photothermal nano-transducer facilitating microsphere expansion through conversion of light energy into the necessary thermal energy. Overall, we’ve demonstrated a novel soft actuation system that retains its expansion capacity with additional coating and incorporation into an elastomer. Chapter 3: Systematic Optimization of Thermally-Expandable Microspheres for Highest Expansion Ratio In our efforts to further explore the properties of thermally-expandable microspheres as a soft actuator we sought to improve the expansion capacity of the microspheres. Here, we systematically modify different parameters involved in the polymerization process of TEMs. Varying the monomer feed ratios containing 2-hydroxyethyl methacrylate, methyl methacrylate and acrylonitrile that form the novel polymer shell blend showed dramatic influences in expansion and microsphere morphology. Switching out the liquid core for a variety of blowing agents of assorted boiling points and molecular structures demonstrated how these factors can potentially improve or impede expansion. We also investigate the impact of a less studied factor of TEMs - the pre-polymerization homogenization time - where we show increasing the time creates microspheres with roughened shapes and mild expansion. Based on these parameters, we optimized the thermally-expandable microsphere for the highest expansion ratio. Chapter 4: Development of Photothermal Responsive Liquid Marble-based Soft Actuators Another intriguing core-shell system is a liquid marble composed of a liquid core coated with superhydrophobic nanoparticles. These flexible systems make the foundation of powering our novel soft actuator devices. Here, we designed a soft actuation system incorporating a liquid marble into a silicone elastomer that can reversibly expand and contract upon heating. To enhance the liquid marble component of the actuator, we made modifications including selection of the nanoparticle shell and developing a method to create a polymer coating around the liquid marble to improve mechanical robustness. Additionally, to increase the photothermal activity capacity for actuation, the water liquid component was swapped for a solution containing graphene nanocolloids paired with a nanoparticle shell containing graphene nanoparticles. The optimized liquid marble was tested in silicone elastomer to produce a bimorph system in which we demonstrate its ability as a soft robot with directed locomotion and to activate a mechanosensitive Piezo protein in a transfected human cell line via photothermal activation. Chapter 5: Synthesis of Novel Photoswitches and Progress Towards their Incorporation in Materials and Photopharmacological Systems As employing light sources to readily induce changes is a key component of our work thus far, we have sought to expand into the domain of photoswitchable molecules. Here, we synthesize such molecules – commonly called photoswitches, with the intention of investigating their photoisomerizing behavior upon variation of functional groups and incorporation into a polymeric material. The conformation changes resulting from isomerization may lead to movement and actuation in bulk materials. For these purposes, so far progress has been made in the design and synthesis of hemithioindigo (HTI) based photoswitches. Another area we are interested in is generating photoswitchable ligand systems that target the dopamine and serotonin receptors currently studied in the Steinhardt lab. To this end, progress towards this goal involved attaching azobenzene-based photoswitches to a commercially available dopamine and serotonin receptor agonists.
Access
Open Access
Recommended Citation
Gomez, Jasmine, "Development and Progress Towards Functional Photoresponsive Systems" (2024). Dissertations - ALL. 1963.
https://surface.syr.edu/etd/1963
