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 - Publisher Copyright:
© 2022 American Chemical Society
PY - 2023
Y1 - 2023
N2 - Inspired by the classic hard−soft acid−base theory and intrigued by a theoretical prediction of spontaneous ion exchange between poly(3,4ethylenedioxythiophene):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(3,4ethylenedioxythiophene):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 - PEDOT:PSS
KW - conductive polymer
KW - ion exchange
KW - ionic liquid
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
VL - 15
SP - 3202
EP - 3213
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 2
ER -