A Study of Ion Conduction Mechanisms and Enhancements in Polymers
Team: Juan Pino, Louise Chen, Howard Katz
Program: Materials Science and Engineering
Thermoelectric materials have the advantage of converting heat into electricity and can be used for heat flux and temperature sensing. These technologies are based on the Seebeck effect, which is a creation of a voltage from a temperature gradient. The voltage is generated as a result of the diffusion of mobile charge carriers transported by the heat flux. Thermoelectric behavior can exhibit two behaviors: n-type (-) or p-type (+). P-type describes a higher concentration of charge carriers on the hot side when a thermal gradient is applied while n-type describes a higher concentration of charge carriers on the cold side as a result of the thermal gradient. Another important quantity is the conductivity which describes the movement of charge carriers across a material as a result of an electric field. Both the conductivity and the Seebeck effect are inversely related and the design of a thermoelectric material often results in the sacrifice of one property.
Ionic Seebeck coefficients in traditional p-type polymer blends demonstrate unstable, short-lasting ionic conductivities. Many of these polymer blends are polar and can be dissolved in water to increase ion conductivity. Although these ion-conducting polymers can exhibit increased ionic conductivity and ionic Seebeck effect with the addition of water, tracking and determining the contributions of ionic conductivity, as well as the Seebeck effect, is often unclear and difficult. It is currently unclear the microscopic changes that occur when a thermal gradient is applied to these ion-conducting polymers. Also, ionic contributions from thermal gradients usually fade exponentially so there is no control over how long the ionic contributions can last in these polymers.
Poly(2-(dimethylamino) ethyl methacrylate)methyl chloride quaternary salt, a highly amorphous polymer that consists of a charged side group and a counterion whereby the latter is the only charge carrier in the polymer matrix, is studied to evaluate the ionic conductivity and ionic Seebeck effect. In addition, we want to determine whether the ionic conductivity and Seebeck can be increased in the presence of FeCl3. Also, we want to understand the mechanism involved in changing the Seebeck coefficient
Juan Pino, Louise Chen, Howard Katz