Hypothesis

The solvation characteristics of poly(ethylene oxide) (PEO) in nanostructured protic ionic liquids (PILs) are driven by polymer-solvent interactions in the polar domains of the PIL. This work hypothesises that the nanostructure of a PIL can be altered via halide addition, directly affecting the solvation of PEO.

Experiments

Small angle neutron scattering (SANS) is used to explore the conformation of 38 kDa PEO dissolved in the PIL propylammonium nitrate (PAN), a mol fraction of 10% propylammonium chloride (PACl) in PAN, and a mole fraction of 10% propylammonium bromide (PABr) in PAN.

Findings

Each of these solutions are shown to behave as a good solvent for PEO, as determined by their Flory exponents and Zimm plot analysis. The quality of solvation is reduced by the addition of the halide salt, with the order of solvation as follows: PAN > Br⁻ addition > Cl⁻ addition. Our experimental observations are consistent with the recently reported solvation structure of PEO in these solutions (Stefanovic et al., 2018). The increased charge density from NO₃⁻ to Br⁻ to Cl⁻ results in greater net ionic interaction between the ionic charge centres. As PEO interacts with PAN primarily through the ammonium hydrogens of the cation, this increased ionic interaction effectively displaces the PEO, resulting in poorer solvation.

中文翻译：

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卤化物对离子液体丙基硝酸铵中聚环氧乙烷溶剂化的影响

假设

聚（环氧乙烷）（PEO）在纳米结构质子离子液体（PIL）中的溶剂化特性是由PIL极性域中的聚合物-溶剂相互作用驱动的。这项工作假设PIL的纳米结构可以通过添加卤化物来改变，直接影响PEO的溶剂化。

实验

小角中子散射（SANS）用于探索溶解在PIL硝酸丙基铵（PAN）中的38 kDa PEO的构象，PAN中10％丙基氯化铵（PACl）的摩尔分数和10％丙基溴化铵的摩尔分数（PAN）中的（PABr）。

发现

根据它们的Flory指数和Zimm图分析，这些溶液均显示出对PEO良好的溶剂作用。溶剂化的质量是通过添加卤化物盐的减少，溶剂化的顺序如下：PAN>溴^-加成>氯^-加成。我们的实验观察结果与最近报道的这些溶液中PEO的溶剂化结构一致（Stefanovic et al。，2018）。增加的电荷密度从NO ₃ ^-以溴^-对氯^-导致离子电荷中心之间更大的净离子相互作用。由于PEO主要通过阳离子的铵氢与PAN相互作用，因此这种增加的离子相互作用有效地取代了PEO，从而导致较差的溶剂化。