An Infrared Spectrocopic Study of a Polyester Copolymer Ionomer Based on Poly(ethylene oxide)

Abstract

A molecular level understanding of the properties of polymer electrolytes can only be obtained through an identification of the types of ionic structures formed in these materials and their relationship to the motion of ions in these systems. Vibrational spectroscopy has proved to be a powerful tool in characterizing such local structures, and a detailed study of the infrared spectrum of a set of sulfonated PEO/aromatic polyesters is presented here. An analysis of the symmetric SO 3 stretching mode revealed no detectable amounts of "free" SO 3 ions in any of the ionomers, but bands due to ion pairs and aggregates were identified. The band due to aggregates increased in intensity relative to the band due to ion pairs as the temperature increased. Vibrational modes due to the poly(ethylene oxide) segments of the copolymers were characteristic of chains in the amorphous state. However, bands due to sequences of trans and gauche O-C-C-O-C-C-O conformations characteristic of the ordered state appeared to be favored upon complexation with ions. The interaction between cations and PEO portions of the chain "locks" the segments in their preferred structure to a large degree, so that compared to non-sulfonated copolymers there are relatively small changes in the relative intensities of conformationally sensitive bands with temperature.

Molecular Volume Effects on the Dynamics of Polymerized Ionic Liquids and their Monomers

“…As opposed to the ILs, the IL monomers and the PILs exhibit a second dipolar relaxation (a 2 ) at lower frequencies, in addition to the segmental relaxation (a) that has the characteristics typical of the glass transition dynamics at higher frequencies. The a 2 process is attributed to ion rearrangement [36,82] (such as, exchanging states between isolated pairs and aggregates of pairs), which is supported by FTIR spectroscopy [83] and linear viscoelastic (LVE) measurements [38,84,85]. Fig.…”

Ionic aggregate dissolution and conduction in a plasticized single-ion polymer conductor

“…Over-subtraction leads to band position shift and shape distortion; under-subtraction fails to make the weak bands of interest more pronounced. 16 This subtraction procedure was also performed for 0% PEG600 and 50% PEG600. Comparison of the FTIR spectrum of PEO600-85%Li plasticized with 25 % PEG600 (purple), PEG600 plasticizer (green), and the ionomer spectra after PEG subtraction (red).…”

“…14,15 Recent Fourier transform infrared spectroscopy (FTIR) studies on the same ionomer detected no free (unassociated SO 3 -) anions. 16,17 Ab initio calculations evaluated the interaction energy between ions and found the majority of Li + ions reside within 0.4 nm of sulfur due to the high ion pair binding energy. 18…”

Fluorinated polysulfonamide based single ion conducting room temperature applicable gel-type polymer electrolytes for lithium ion batteries

“…For a successful implementation of single lithium ion conducting polymer electrolytes, various concepts were proposed. Different anionic anchor groups carrying Li ions may be utilized, including carboxyl groups, sulfonate groups, 15,[19][20][21][22] bis(sulfonyl)imides 15,[23][24][25][26][27] and sp 3 boron species. 15,[28][29][30][31] In the case of carboxyl and sulfonate groups, the Li ions strongly associate with the anions so that merely a low concentration of free Li ions is present.…”

“…15,[28][29][30][31] In the case of carboxyl and sulfonate groups, the Li ions strongly associate with the anions so that merely a low concentration of free Li ions is present. 19,32 The B-O bond in boron based anions, however, is highly moisture sensitive; therefore long-term electrochemical stability appears questionable. 14 In view of the rather favorable properties in terms of high ion dissociation degrees, bis(sulfonyl)imides are considered as versatile anionic moieties.…”