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Date of Award
Master of Science (MS)
Murphy, Amanda R.
Rider, David A. (Materials scientist)
In order to produce conductive, biocompatible and mechanically robust materials for use in bioelectrical applications, we have developed a new strategy to selectively incorporate poly(pyrrole) (Ppy) into constructs made from silk fibroin. Here, we demonstrate that covalent attachment of negatively charged, hydrophilic sulfonic acid groups to the silk protein can selectively promote pyrrole absorption and polymerization within the modified films to form a conductive, interpenetrating network of Ppy and silk that is incapable of delamination. To further increase the conductivity and long-term stability of the Ppy network, a variety of small molecule sulfonic acid dopants were utilized and the properties of these silk-conducting polymer composites were monitored over time. The composites were evaluated using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), optical microscopy, energy dispersive X-ray (EDX) spectroscopy, cyclic voltammetry, 4-point resistivity probe and mechanical testing. In addition, the performance was evaluated following exposure to several biologically relevant enzymes. Using this strategy, we are able to produce mechanically robust polymer electrodes in a variety of geometries with stable electrochemical performance and sheet resistivities on the order of 102 Ω/sq (conductivity ~1 S/cm). We adapted anisotropic versions of our silk-Ppy composites to construct electrically-controlled actuators that exhibit repeated bending movements under applied currents less than 5 mA, and potentials between 1 and 4 V. These bilayer actuators function through anion exchange in biologically-relevant electrolytes, and show promise for fully biocompatible actuator systems.
Western Washington University
Copying of this thesis in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Romero, Isabella S., "Silk fibroin-based conducting polymer composite electrodes and their use as electromechanical actuators" (2013). WWU Graduate School Collection. 280.