Browsing by Author "Boothby, Jennifer M."
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Item Engineering Liquid Crystalline Polymers for Biological Applications(Society for Biomaterials, 2019-04) Boothby, Jennifer M.; Ambulo, Cedric P.; Saed, M.; Ware, Taylor H.; Boothby, Jennifer M.; Ambulo, Cedric P.; Ware, Taylor H.Statement of Purpose: Large, bulky, power-hungry traditional mechanical actuators are poorly suited for small, biological applications such as medical devices. Shape changing polymers are an emerging class of actuators which can utilize environmental conditions to undergo large, complex shape changes. Liquid crystalline self-assembly is one promising strategy to program structural orientation and resulting actuation in polymeric materials. This molecular ordering can be spatially patterned, resulting in monolithic materials that undergo complex shape change. However, liquid crystal polymer networks are typically hydrophobic and only respond to stimuli that would be incompatible with biological environments, such as high temperatures and organic solvents. We have used two strategies to overcome these limitations: 1) engineering liquid crystal elastomers chemistry to respond near body temperature and 2) building gels from water-soluble, chromonic liquid crystals to respond to aqueous stimuli.Item Molecularly-ordered Hydrogels with Controllable, Anisotropic Stimulus Response(Royal Society of Chemistry, 2019-05-03) Boothby, Jennifer M.; Samuel, Jeremy; Ware, Taylor H.; 0000-0001-7996-7393 (Ware, TH); 0000-0003-3095-0640 (Boothby, JM); Boothby, Jennifer M.; Samuel, Jeremy; Ware, Taylor H.Hydrogels which morph between programmed shapes in response to aqueous stimuli are of significant interest for biosensors and artificial muscles, among other applications. However, programming hydrogel shape change at small size scales is a significant challenge. Here we use the inherent ordering capabilities of liquid crystals to create a mechanically anisotropic hydrogel; when coupled with responsive comonomers, the mechanical anisotropy in the network guides shape change in response to the desired aqueous condition. Our synthetic strategy hinges on the use of a methacrylic chromonic liquid crystal monomer which can be combined with a non-polymerizable chromonic of similar structure to vary the magnitude of shape change while retaining liquid crystalline order. This shape change is directional due to the mechanical anisotropy of the gel, which is up to 50% stiffer along the chromonic stack direction than perpendicular. Additionally, we show that the type of stimulus to which these anisotropic gels respond can be switched by incorporating responsive, hydrophilic comonomers without destroying the nematic phase or alignment. The utility of these properties is demonstrated in polymerized microstructures which exhibit Gaussian curvature in response to high pH due to emergent ordering in a micron-sized capillary. © 2019 The Royal Society of Chemistry.Item Water-Responsive Liquid Crystal Polymers for Biological Applications(2019-07-16) Boothby, Jennifer M.; Ware, Taylor H.Materials which change shape in response to stimuli can perform work as artificial muscles, dynamic medical device coatings, and inducible drug delivery vehicles. Traditional actuators are unsuitable for applications in biological environments due to their large size, high power requirements, and incompatibility with aqueous environments. Developing small, untethered actuators which respond to biocompatible stimuli is essential to drive progress in materials engineering for biomedical applications. Polymers have shown promise as actuators enabled by changes in their environment; Shape memory polymers, hydrogels, and liquid crystal polymers rely on stimuli, such as heat, light, and chemical gradients to actuate. However, these emergent smart materials require further development to serve functional applications. Liquid crystal polymers have emerged as particularly promising smart materials because reversible shape change can be hardcoded into the molecular orientation, unlike shape memory polymers or hydrogels. The aim of my research is to use the self-assembly of liquid crystals to synthesize materials which can selectively actuate in biological and water-based environments.