Despite the great interest in nanoconfined materials nowadays, nanocompartmentalized poly(ionic liquid)s (PILs) have been rarely investigated so far. Herein, we report on the successful alkylation of poly(1-vinylimidazole) with methyl iodide in bicontinuous nanophasic poly(1-vinylimidazole)-l-poly(tetrahydrofuran) (PVIm-l-PTHF) amphiphilic conetworks (APCNs) to obtain nanoconfined methylated PVImMe-l-PTHF poly(ionic liquid) conetworks (PIL-CNs). A high extent of alkylation (~95%) was achieved via a simple alkylation process with MeI at room temperature. This does not destroy the bicontinuous nanophasic morphology as proved by SAXS and AFM, and PIL-CNs with 15–20 nm d-spacing and poly(3-methyl-1-vinylimidazolium iodide) PIL nanophases with average domain sizes of 8.2–8.4 nm are formed. Unexpectedly, while the swelling capacity of the PIL-CN dramatically increases in aprotic polar solvents, such as DMF, NMP, and DMSO, reaching higher than 1000% superabsorbent swelling degrees, the equilibrium swelling degrees decrease in even highly polar protic (hydrophilic) solvents, like water and methanol. An unprecedented Gaussian-type relationship was found between the ratios of the swelling degrees versus the polarity index, indicating increased swelling for the nanoconfined PVImMe-l-PTHF PIL-CNs in solvents with a polarity index between ~6 and 9.5. In addition to the nanoconfined structural features, the unique selective superabsorbent swelling behavior of the PIL-CNs can also be utilized in various application fields.
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Acknowledgments: The authors gratefully acknowledge the elemental analyses by H. Medzihradszky-Schweiger, and the support by the European Research Area Chemistry (ERA-Chemistry) program, the National Research, Development and Innovation Office, Hungary (NN116252, NN129366), and the German Research Foundation (DFG; MU 836/13-1, 269965048). A. Wacha acknowledges the postdoctoral support by the NRDIO, Hungary (PD124451).
Funding: This research was funded by the National Research, Development and Innovation Office (NRDIO), Hungary (NN116252, NN129366), and the German Research Foundation (DFG; MU 836/13-1, 269965048) in the framework of the European Research Area Chemistry (ERA-Chemistry) and the NRDIO’s international cooperation programs.
© 2020 by the authors. Licensee MDPI, Basel, Switzerland.
- Amphiphilic conetworks
- Nanoconfined poly(ionic liquid)
- Nanophase-separated structure
- Selective swelling