TY - JOUR
T1 - A Reversible Structural Phase Transition by Electrochemically-Driven Ion Injection into a Conjugated Polymer
AU - Bischak, Connor G.
AU - Flagg, Lucas Q.
AU - Yan, Kangrong
AU - Rehman, Tahir
AU - Davies, Daniel W.
AU - Quezada, Ramsess J.
AU - Onorato, Jonathan W.
AU - Luscombe, Christine K.
AU - Diao, Ying
AU - Li, Chang Zhi
AU - Ginger, David S.
N1 - Funding Information:
L.Q.F and R.J.Q.’s contributions began as exploratory work under the expired National Science Foundation award, NSF DMR-1607242, and were subsequently supported partly from NWIMPACT SEED award funding. C.G.B. is a Washington Research Foundation Postdoctoral Fellow. Y.K., T.R., and C.-Z.L. thank the support from National Natural Science Foundation of China (Nos. 21722404 and 21674093) for supporting synthesis of the PB2T-TEG polymer. Y.D. and D.W.D. acknowledge support by the Sloan Foundation through the Sloan Research Fellowship in Chemistry and 3M Nontenured Faculty Award contributing to analysis of the XRD data and interpretation of the phase-change mechanism. J.O. and C.K.L.’s contributions are based in part on work supported by the National Science Foundation, DMR-1629369. The photoinduced force microscopy (PiFM) and X-ray diffraction (XRD) were conducted at the Molecular Analysis Facility, a National Nanotechnology Coordinated Infrastructure site at the University of Washington that is supported in part by the National Science Foundation (grant ECC-1542101), the University of Washington, the Molecular Engineering & Sciences Institute, the Clean Energy Institute and the National Institutes of Health. This research used beamline 7.3.3 of the Advanced Light Source (ALS), which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. The authors thank C. Zhu and E. Schaible at the ALS for assistance with (GI)WAXS data acquisition and analysis.
PY - 2020/4/22
Y1 - 2020/4/22
N2 - We find that conjugated polymers can undergo reversible structural phase transitions during electrochemical oxidation and ion injection. We study poly[2,5-bis(thiophenyl)-1,4-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)benzene] (PB2T-TEG), a conjugated polymer with glycolated side chains. Using grazing incidence wide-angle X-ray scattering (GIWAXS), we show that, in contrast to previously known polymers, this polymer switches between two structurally distinct crystalline phases associated with electrochemical oxidation/reduction in an aqueous electrolyte. Importantly, we show that this unique phase change behavior has important physical consequences for ion-polaron pair transport. Notably, using moving front experiments visualized by both optical microscopy and super-resolution photoinduced force microscopy (PiFM), we show that a laterally propagating ion-polaron pair front in PB2T-TEG exhibits non-Fickian transport, retaining a sharp step-edge profile, in stark contrast to the Fickian diffusion more commonly observed in polymers like P3MEEMT. This structural phase transition is reminiscent of those accompanying ion uptake in inorganic materials like LiFePO4. We propose that the engineering of similar properties in future conjugated polymers may enable the realization of new materials with superior performance in electrochemical energy storage or neuromorphic memory applications.
AB - We find that conjugated polymers can undergo reversible structural phase transitions during electrochemical oxidation and ion injection. We study poly[2,5-bis(thiophenyl)-1,4-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)benzene] (PB2T-TEG), a conjugated polymer with glycolated side chains. Using grazing incidence wide-angle X-ray scattering (GIWAXS), we show that, in contrast to previously known polymers, this polymer switches between two structurally distinct crystalline phases associated with electrochemical oxidation/reduction in an aqueous electrolyte. Importantly, we show that this unique phase change behavior has important physical consequences for ion-polaron pair transport. Notably, using moving front experiments visualized by both optical microscopy and super-resolution photoinduced force microscopy (PiFM), we show that a laterally propagating ion-polaron pair front in PB2T-TEG exhibits non-Fickian transport, retaining a sharp step-edge profile, in stark contrast to the Fickian diffusion more commonly observed in polymers like P3MEEMT. This structural phase transition is reminiscent of those accompanying ion uptake in inorganic materials like LiFePO4. We propose that the engineering of similar properties in future conjugated polymers may enable the realization of new materials with superior performance in electrochemical energy storage or neuromorphic memory applications.
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U2 - 10.1021/jacs.9b12769
DO - 10.1021/jacs.9b12769
M3 - Article
C2 - 32227841
AN - SCOPUS:85088981286
VL - 142
SP - 7434
EP - 7442
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 16
ER -