The infinite dilution radii of gyration (R_g,0) for five different molecular weights (10–250 kg/mol) of perdeuterated poly(ethylene oxide) (d-PEO) have been determined at 80 °C in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF₄]) using small-angle neutron scattering (SANS). The results establish the dependence of R_g,0 on polymer molecular weight as R_g,0 ∼ M_w^0.55. An excluded volume exponent of ν ≈ 0.55 indicates that [BMIM][BF₄] is a moderately good solvent and that PEO remains a flexible random coil in this ionic liquid. These results clarify the uncertainty surrounding PEO coil dimensions in this ionic liquid, as computer simulations at various levels of complexity have led to conflicting results, and prior experimental results also do not present a completely consistent picture.

中文翻译：

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小角度中子散射在离子液体中聚环氧乙烷的线圈尺寸

在80°C的离子液体中，确定了五种不同分子量（10–250 kg / mol）氘代聚环氧乙烷（d -PEO）的无限旋转回旋半径（R _g，0）。使用小角中子散射（SANS）的三氟丁基丁基3-甲基咪唑鎓四氟硼酸盐（[BMIM] [BF ₄ ]）。结果建立的依赖性ř_克，0上的聚合物分子量为ř_克，0〜中号_瓦特^0.55。排除的体积指数ν≈0.55表示[BMIM] [BF ₄是适度良好的溶剂，而PEO在这种离子液体中仍是柔性无规卷曲。这些结果阐明了这种离子液体中PEO线圈尺寸的不确定性，因为在各种复杂程度下的计算机模拟都导致了相互矛盾的结果，并且先前的实验结果也无法提供完全一致的图像。