Li Chenming, Bhandary Rajesh, Marinow Anja, Bachmann Stephanie, Pöppler Ann-Christin, Binder Wolfgang H
Macromolecular Chemistry, Institute of Chemistry, Faculty of Natural Science II (Chemistry, Physics and Mathematics), Martin Luther University Halle-Wittenberg, von-Danckelmann-Platz 4, D-06120, Halle (Saale), Germany.
Institute of Organic Chemistry, Faculty of Chemistry and Pharmacy, University of Würzburg, Am Hubland, 97074, Würzburg, Germany.
Macromol Rapid Commun. 2024 Jan;45(2):e2300464. doi: 10.1002/marc.202300464. Epub 2023 Oct 17.
Hydrogen bonds (H-bonds) are highly sensitive to the surrounding environments owing to their dipolar nature, with polar solvents kown to significantly weaken H-bonds. Herein, the stability of the H-bonding motif ureidopyrimidinone (UPy) is investigated, embedded into a highly polar polymeric ionic liquid (PIL) consisting of pendant pyrrolidinium bis(trifluoromethylsulfonyl)imide (IL) moieties, to study the influence of such ionic environments on the UPy H-bonds. The content of the surrounding IL is changed by addition of an additional low molecular weight IL to further boost the IL content around the UPy moieties in molar ratios of UPy/IL ranging from 1/4 up to 1/113, thereby promoting the polar microenvironment around the UPy-H-bonds. Variable-temperature solid-state MAS NMR spectroscopy and FT-IR spectroscopy demonstrate that the UPy H-bonds are largely present as (UPy-) dimers, but sensitive to elevated temperatures (>70 °C). Subsequent rheology and DSC studies reveal that the ILs only solvate the polymeric chains but do not interfere with the UPy-dimer H-bonds, thus accounting for their high stability and applicability in many material systems.
氢键（H键）由于其偶极性质而对周围环境高度敏感，已知极性溶剂会显著削弱氢键。在此，研究了嵌入由侧链吡咯烷鎓双（三氟甲基磺酰）亚胺（IL）部分组成的高极性聚合离子液体（PIL）中的脲嘧啶酮（UPy）氢键基序的稳定性，以研究这种离子环境对UPy氢键的影响。通过添加额外的低分子量IL来改变周围IL的含量，以进一步提高UPy部分周围的IL含量，UPy/IL的摩尔比范围从1/4到1/113，从而促进UPy氢键周围的极性微环境。变温固态MAS NMR光谱和FT-IR光谱表明，UPy氢键主要以（UPy-）二聚体形式存在，但对升高的温度（>70°C）敏感。随后的流变学和DSC研究表明，IL仅使聚合物链溶剂化，但不干扰UPy-二聚体氢键，因此说明了它们在许多材料体系中的高稳定性和适用性。
