TY - JOUR
T1 - Protic Ionic Liquids for Intrinsically Stretchable Conductive Polymers
AU - Kim, Minji
AU - Lee, Seung Yeob
AU - Kim, Jihyun
AU - Choi, Changwon
AU - Lansac, Yves
AU - Ahn, Hyungju
AU - Park, Sohee
AU - Jang, Yun Hee
AU - Lee, Seoung Ho
AU - Lee, Byoung Hoon
N1 - Funding Information:
This work was supported by the National Research Foundation of Korea funded by the Ministry of Science and ICT (2019M3C1B8090804, 2019R1C1C1010426, 2022R1A4A2000835, 2019R1I1A3A01058982, and 2019R1A2C2003118). B.H.L. acknowledges partial support from the BK21 FOUR (Fostering Outstanding Universities for Research) funded by the Ministry of Education (MOE, Korea) and National Research Foundation of Korea (NRF-5199990614253, Education Research Center for 4IR-Based Health Care).
Publisher Copyright:
© 2022 American Chemical Society.
PY - 2022
Y1 - 2022
N2 - Inspired by the classic hard-soft acid-base theory and intrigued by a theoretical prediction of spontaneous ion exchange between poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and hard-cation-soft-anion ionic liquid (IL), we treat PEDOT:PSS with a new IL composed of a protic (i.e., extremely hard) cation (3-methylimidazolium, p-MIM+) and an extremely soft anion (tetracyanoborate, TCB-). In fact, this protic IL (p-MIM:TCB) accomplishes the same levels of ion-exchange-mediated PEDOT-PSS separation, PEDOT-rich nanofibril formation, and electrical conductivity enhancement (∼2500 S/cm) as its aprotic counterpart (EMIM:TCB with 1-ethyl-3-methylimidazolium), the best IL used for this purpose so far. Furthermore, p-MIM:TCB significantly outperforms EMIM:TCB in terms of improving the stretchability (i.e., the highest tensile strain) of the PEDOT:PSS thin film. This enhancement is a result of the aromatic and protic cation p-MIM+, which acts as a molecular adhesive holding the exchanged ion pairs (PEDOT+:TCB- - -p-MIM+:PSS-) via ionic intercalation (at the surface of TCB-decorated PEDOT+ clusters) and hydrogen bonding (to PSS-), in which washing p-MIM+ out of the film degrades the stretchability while keeping the morphology. Our results offer molecular-level insight into the morphological, electrical, and mechanical properties of PEDOT:PSS and a molecular-interaction-based enhancement strategy that can be used for intrinsically stretchable conductive polymers.
AB - Inspired by the classic hard-soft acid-base theory and intrigued by a theoretical prediction of spontaneous ion exchange between poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and hard-cation-soft-anion ionic liquid (IL), we treat PEDOT:PSS with a new IL composed of a protic (i.e., extremely hard) cation (3-methylimidazolium, p-MIM+) and an extremely soft anion (tetracyanoborate, TCB-). In fact, this protic IL (p-MIM:TCB) accomplishes the same levels of ion-exchange-mediated PEDOT-PSS separation, PEDOT-rich nanofibril formation, and electrical conductivity enhancement (∼2500 S/cm) as its aprotic counterpart (EMIM:TCB with 1-ethyl-3-methylimidazolium), the best IL used for this purpose so far. Furthermore, p-MIM:TCB significantly outperforms EMIM:TCB in terms of improving the stretchability (i.e., the highest tensile strain) of the PEDOT:PSS thin film. This enhancement is a result of the aromatic and protic cation p-MIM+, which acts as a molecular adhesive holding the exchanged ion pairs (PEDOT+:TCB- - -p-MIM+:PSS-) via ionic intercalation (at the surface of TCB-decorated PEDOT+ clusters) and hydrogen bonding (to PSS-), in which washing p-MIM+ out of the film degrades the stretchability while keeping the morphology. Our results offer molecular-level insight into the morphological, electrical, and mechanical properties of PEDOT:PSS and a molecular-interaction-based enhancement strategy that can be used for intrinsically stretchable conductive polymers.
KW - conductive polymer
KW - ion exchange
KW - ionic liquid
KW - PEDOT:PSS
KW - stretchable electrode
UR - http://www.scopus.com/inward/record.url?scp=85143866805&partnerID=8YFLogxK
U2 - 10.1021/acsami.2c17376
DO - 10.1021/acsami.2c17376
M3 - Article
C2 - 36484468
AN - SCOPUS:85143866805
SN - 1944-8244
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
ER -