Proton-Exchange-Induced Configuration Rearrangement in a Poly(ionic liquid) Solution: A NMR Study

TY - JOUR

T1 - Proton-Exchange-Induced Configuration Rearrangement in a Poly(ionic liquid) Solution

T2 - A NMR Study

AU - Zhu, Haijin

AU - Yang, Hengrui

AU - Li, Jiaye

AU - Barlow, Kristine J.

AU - Kong, Lingxue

AU - Mecerreyes, David

AU - MacFarlane, Douglas R.

AU - Forsyth, Maria

N1 - Publisher Copyright: © 2017 American Chemical Society.

PY - 2017/11/2

Y1 - 2017/11/2

N2 - Polymeric ionic liquids have emerged recently as a promising alternative to traditional polymers as the polymer electrolyte membrane materials of choice because of their strongly decoupled dynamics between the polymer backbone and the counterions. Knowledge of proton exchange and transport mechanism in such materials is critical to the design and development of new poly(ionic liquid) materials with improved electrochemical properties. Our NMR results show that the proton exchange between the labile proton of the diethylmethylammonium (NH122) cation and H2O molecules is accompanied by a concerted configuration rearrangement of the ammonium. Through a combination of PFG-NMR and proton relaxation (line width) analysis, we demonstrate that at lower temperatures the labile proton diffuses along with the NH122 ammonium cation as an integral unit, whereas at higher temperatures the NH/H2O proton exchange sets in gradually, and the PFG-NMR measured diffusion coefficient is a population-averaged value between the two exchanging sites.

AB - Polymeric ionic liquids have emerged recently as a promising alternative to traditional polymers as the polymer electrolyte membrane materials of choice because of their strongly decoupled dynamics between the polymer backbone and the counterions. Knowledge of proton exchange and transport mechanism in such materials is critical to the design and development of new poly(ionic liquid) materials with improved electrochemical properties. Our NMR results show that the proton exchange between the labile proton of the diethylmethylammonium (NH122) cation and H2O molecules is accompanied by a concerted configuration rearrangement of the ammonium. Through a combination of PFG-NMR and proton relaxation (line width) analysis, we demonstrate that at lower temperatures the labile proton diffuses along with the NH122 ammonium cation as an integral unit, whereas at higher temperatures the NH/H2O proton exchange sets in gradually, and the PFG-NMR measured diffusion coefficient is a population-averaged value between the two exchanging sites.

UR - http://www.scopus.com/inward/record.url?scp=85032821287&partnerID=8YFLogxK

U2 - 10.1021/acs.jpclett.7b02439

DO - 10.1021/acs.jpclett.7b02439

M3 - 文章

C2 - 29039670

AN - SCOPUS:85032821287

SN - 1948-7185

VL - 8

SP - 5355

EP - 5359

JO - Journal of Physical Chemistry Letters

JF - Journal of Physical Chemistry Letters

IS - 21

ER -