TY - JOUR
T1 - Thermal and ion transport properties of hydrophilic and hydrophobic polymerized styrenic imidazolium ionic liquids
AU - Weber, Ryan L.
AU - Ye, Yuesheng
AU - Banik, Steven M.
AU - Elabd, Yossef A.
AU - Hickner, Michael A.
AU - Mahanthappa, Mahesh K.
PY - 2011/9/15
Y1 - 2011/9/15
N2 - Polymerized ionic liquids (PILs) are a platform for fundamental studies of structure-property relationships in single ion conductors, with potential applications in energy storage and conversion. The synthesis, thermal properties, and ionic conductivities of homologous, narrow dispersity styrenic PILs are described. Hydrophilic poly(4-vinylbenzyl alkylimidazolium chloride) (PVBn(alkyl)ImCl) homopolymers with constant average degrees of polymerization were synthesized by post-synthetic functionalization of a poly(4-vinylbenzyl chloride) (Mn = 15.9 kg/mol, Mw/Mn = 1.34) master batch with N-alkylimidazoles (alkyl = -CH3 (Me), -C 4H9 (Bu), and -C6H13 (Hex)). The chloride counterions of PVBnHexImCl were exhaustively metathesized with PFa 4-, PFa6-, and bis(trifluoromethanesulfonyl)imide (TFSI-) to yield a series of hydrophobic PILs. Thermogravimetric analyses indicate that PVBn(alkyl)ImCl homopolymers are unstable above 220 °C, whereas the hydrophobic PILs remain stable up to 290 °C. The glass transition temperatures (Tg) decrease with both increasing alkyl side-chain length and increasing counterion size, exemplified by Tg = 9 °C for PVBnHexImTFSI. Hydrophilic PILs exhibit high ionic conductivities (as high as ∼0.10 S cm-1) that depend on the relative humidity, water uptake, and the PIL side chain length. The hydrophobic PILs exhibit lower conductivities (up to ∼5 × 10-4 S cm-1) that depend predominantly on the polymer Tg, however, counterion size and symmetry also contribute.
AB - Polymerized ionic liquids (PILs) are a platform for fundamental studies of structure-property relationships in single ion conductors, with potential applications in energy storage and conversion. The synthesis, thermal properties, and ionic conductivities of homologous, narrow dispersity styrenic PILs are described. Hydrophilic poly(4-vinylbenzyl alkylimidazolium chloride) (PVBn(alkyl)ImCl) homopolymers with constant average degrees of polymerization were synthesized by post-synthetic functionalization of a poly(4-vinylbenzyl chloride) (Mn = 15.9 kg/mol, Mw/Mn = 1.34) master batch with N-alkylimidazoles (alkyl = -CH3 (Me), -C 4H9 (Bu), and -C6H13 (Hex)). The chloride counterions of PVBnHexImCl were exhaustively metathesized with PFa 4-, PFa6-, and bis(trifluoromethanesulfonyl)imide (TFSI-) to yield a series of hydrophobic PILs. Thermogravimetric analyses indicate that PVBn(alkyl)ImCl homopolymers are unstable above 220 °C, whereas the hydrophobic PILs remain stable up to 290 °C. The glass transition temperatures (Tg) decrease with both increasing alkyl side-chain length and increasing counterion size, exemplified by Tg = 9 °C for PVBnHexImTFSI. Hydrophilic PILs exhibit high ionic conductivities (as high as ∼0.10 S cm-1) that depend on the relative humidity, water uptake, and the PIL side chain length. The hydrophobic PILs exhibit lower conductivities (up to ∼5 × 10-4 S cm-1) that depend predominantly on the polymer Tg, however, counterion size and symmetry also contribute.
KW - conducting polymers
KW - controlled polymerization
KW - ionomers
KW - polyelectrolytes
KW - radical polymerization
KW - single ion conductor
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U2 - 10.1002/polb.22319
DO - 10.1002/polb.22319
M3 - Article
AN - SCOPUS:80051757135
SN - 0887-6266
VL - 49
SP - 1287
EP - 1296
JO - Journal of Polymer Science, Part B: Polymer Physics
JF - Journal of Polymer Science, Part B: Polymer Physics
IS - 18
ER -