Rachel Pytel - Academia.edu (original) (raw)
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Papers by Rachel Pytel
... www.ilabnotebook.com) 5. Strategies to migrate towards an electronic lab notebook One of thed... more ... www.ilabnotebook.com) 5. Strategies to migrate towards an electronic lab notebook One of thedifficulties in implementing ... for example, the chemists must be able to input the names of chemicals and not have the handwriting-to-text ... [17] Stember, R. LABTrack: Introducing a legal ...
Polymer, 2008
Free-standing polypyrrole films have been stretched or cold rolled to produce uniaxially and biax... more Free-standing polypyrrole films have been stretched or cold rolled to produce uniaxially and biaxially textured films. The oriented films show an increase in conductivity up to 3Â when compared to unprocessed films, due to polymer chain alignment. Highly anisotropic active stress and strain are observed for the textured films, with up to 7Â larger active strains transverse to the orientation direction. This anisotropy results in a 100% increase in active stress and 70% increase in active strain when compared to unprocessed films, and active strains over 10% (when cycled at 0.1 V/s) have been achieved with this method.
Polypyrrole has been extensively studied as an electroactive material, but these studies have pro... more Polypyrrole has been extensively studied as an electroactive material, but these studies have provided little insight to the influence that morphology has on actuation at the nanoscale. By discovering and exploiting the connection between nanoscale transport events and macroscale active strain, we can learn how to process polypyrrole and other conducting polymers for improved electroactive device performance. We show that by controlling polymer chain configuration and packing, a conducting polymer actuator can be engineered that shows a significantly larger macroscopic electroactive response for a given set of driving conditions. We utilize different modes of deformation to impart orientation textures that can be observed via synchrotron x-ray diffraction and electronic and ionic resistance measurements. Certain textures enhance pathways for ion transport between polymer chains, resulting in an anisotropic electroactive strain response that can be harnessed when making polypyrrole-driven devices. This response provides valuable insight to the mechanism of polypyrrole actuation on the nanoscale, supporting a mechanism where counterions migrate to locations between the oriented polymer chains.
Chemistry of Materials, 2006
... Rachel Pytel,* Edwin Thomas, and Ian Hunter . Institute ... As the degree of elongatio... more ... Rachel Pytel,* Edwin Thomas, and Ian Hunter . Institute ... As the degree of elongation is increased, the isotropic rings observable in the first image separate into arcs that are perpendicular or parallel to the direction of stretch. In ...
Polymer, 2008
Polypyrrole is a leading conducting polymer actuator, but the factors that influence its performa... more Polypyrrole is a leading conducting polymer actuator, but the factors that influence its performance when actuated under load in devices (such as the polymer stiffness) are not yet fully understood. To this end, we have probed the dynamic elastic modulus of polypyrrole in situ during actuation in a variety of electrolytes. As part of this study, we demonstrate that the electroactive response in dilute 1-butyl-3-methylimidazolium hexafluorophosphate can be changed from cation-to anion-dominated by adjusting the applied potential waveform. We observe that when conservative electrochemical conditions are applied in order to avoid dual ion movement or significant transfer of neutral solvent, the stiffness is determined by level of counterion swelling. The elastic modulus decreases during the net influx of ions into the bulk polymer and increases as these ions are expelled, regardless of whether the electroactive response is cation-or anion-dominated or whether there is a neutral solvent present in the electrolyte. This effect is quite significant, and we have observed up to a 3Â increase in elastic modulus upon actuation in neat 1-butyl-3-methylimidazolium hexafluorophosphate.
... www.ilabnotebook.com) 5. Strategies to migrate towards an electronic lab notebook One of thed... more ... www.ilabnotebook.com) 5. Strategies to migrate towards an electronic lab notebook One of thedifficulties in implementing ... for example, the chemists must be able to input the names of chemicals and not have the handwriting-to-text ... [17] Stember, R. LABTrack: Introducing a legal ...
Polymer, 2008
Free-standing polypyrrole films have been stretched or cold rolled to produce uniaxially and biax... more Free-standing polypyrrole films have been stretched or cold rolled to produce uniaxially and biaxially textured films. The oriented films show an increase in conductivity up to 3Â when compared to unprocessed films, due to polymer chain alignment. Highly anisotropic active stress and strain are observed for the textured films, with up to 7Â larger active strains transverse to the orientation direction. This anisotropy results in a 100% increase in active stress and 70% increase in active strain when compared to unprocessed films, and active strains over 10% (when cycled at 0.1 V/s) have been achieved with this method.
Polypyrrole has been extensively studied as an electroactive material, but these studies have pro... more Polypyrrole has been extensively studied as an electroactive material, but these studies have provided little insight to the influence that morphology has on actuation at the nanoscale. By discovering and exploiting the connection between nanoscale transport events and macroscale active strain, we can learn how to process polypyrrole and other conducting polymers for improved electroactive device performance. We show that by controlling polymer chain configuration and packing, a conducting polymer actuator can be engineered that shows a significantly larger macroscopic electroactive response for a given set of driving conditions. We utilize different modes of deformation to impart orientation textures that can be observed via synchrotron x-ray diffraction and electronic and ionic resistance measurements. Certain textures enhance pathways for ion transport between polymer chains, resulting in an anisotropic electroactive strain response that can be harnessed when making polypyrrole-driven devices. This response provides valuable insight to the mechanism of polypyrrole actuation on the nanoscale, supporting a mechanism where counterions migrate to locations between the oriented polymer chains.
Chemistry of Materials, 2006
... Rachel Pytel,* Edwin Thomas, and Ian Hunter . Institute ... As the degree of elongatio... more ... Rachel Pytel,* Edwin Thomas, and Ian Hunter . Institute ... As the degree of elongation is increased, the isotropic rings observable in the first image separate into arcs that are perpendicular or parallel to the direction of stretch. In ...
Polymer, 2008
Polypyrrole is a leading conducting polymer actuator, but the factors that influence its performa... more Polypyrrole is a leading conducting polymer actuator, but the factors that influence its performance when actuated under load in devices (such as the polymer stiffness) are not yet fully understood. To this end, we have probed the dynamic elastic modulus of polypyrrole in situ during actuation in a variety of electrolytes. As part of this study, we demonstrate that the electroactive response in dilute 1-butyl-3-methylimidazolium hexafluorophosphate can be changed from cation-to anion-dominated by adjusting the applied potential waveform. We observe that when conservative electrochemical conditions are applied in order to avoid dual ion movement or significant transfer of neutral solvent, the stiffness is determined by level of counterion swelling. The elastic modulus decreases during the net influx of ions into the bulk polymer and increases as these ions are expelled, regardless of whether the electroactive response is cation-or anion-dominated or whether there is a neutral solvent present in the electrolyte. This effect is quite significant, and we have observed up to a 3Â increase in elastic modulus upon actuation in neat 1-butyl-3-methylimidazolium hexafluorophosphate.