Aqueous SEC–MALS Characterization of Hydrophilic Azolium-Based Poly(ionic liquid)s in Their Native Halide Form
Year: 2026
Type: preprint
Abstract: The molar-mass characterization of hydrophilic poly(ionic liquid)s (PILs) is challenging due to strong polymer–column interactions and low refractive-index contrast, which limit detector sensitivity. To address these limitations, we analyzed five imidazolium-based PILs using both aqueous and organic (THF/LiTFSI) size-exclusion chromatography (SEC) with polystyrene calibration or multi-angle light-scattering detection (SEC-MALS). In THF/LiTFSI, the low dn/dc values compromised sensitivity, hindering reliable molar-mass determination. We therefore screened various aqueous mobile phases to identify optimal elution conditions. Among those tested, 0.3 M formic acid yielded well-resolved polymer peaks for all five PILs, with significantly higher dn/dc values than THF/LiTFSI. Mass recoveries ranged from 60.5% to 78.5%, enabling accurate molarmass determination. The method was also qualitatively validated for poly(vinylimidazole), partially quaternized poly(vinylimidazole), and a poly(thiazolium). Overall, aqueous SEC with 0.3 M formic acid emerges as a simple, general, and efficient alternative for the SECMALS characterization of hydrophilic azolium-based homo- and co-PILs. Unlike organic SEC, this approach requires no prior counteranion exchange, thus streamlining the analytical workflow.
Source: ChemRxiv
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223278806