Correlating molecular architecture of a radical polymer based copolymer with its electrical transport properties
The design and synthesis of electrically-conductive macromolecules can lead to significant improvements in the performance of polymer-based energy conversion devices (e.g., thermoelectric devices). For these organic electronic devices, conjugated polymers have dominated the area of conductive polymers; however, these materials are usually synthesized using conditions that lead to poorly-defined polymers. Furthermore, in these increasingly-standard polymers, the charge transport ability of the polymer thin films is largely affected by the degree of crystallinity, which is a difficult property to control in a reproducible fashion. Therefore, we seek to explore a new class of amorphous, non-conjugated polymers containing a stable radical moiety within the pendant groups (i.e., radical polymers). Among this emerging class of polymers, poly(2,2,6,6-tetramethylpiperinidyloxyl methacrylate) (PTMA) has been used widely in the field of organic radical batteries with high performance metrics being achieved. However, knowledge of the transport properties of PTMA in the solid state is lacking. To this end, we have synthesized PTMA and evaluated the transport properties of this polymer in the pristine and doped state. More specifically, we have incorporated carbon-based dopants with sulfonic functional groups within the polymer chains. Then, we established how the molecular structure of the copolymer and functionality of the pendant group affect the hole mobility of the copolymer thin film. Through this methodology, we have been able to develop structure-property relationships of the copolymer in order to elucidate how molecular control dictates macroscopic device performance.
Boudouris, Purdue University.
Organic chemistry|Polymer chemistry|Chemical engineering
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