–SO₂NHSO₂C₄F₉/CF₃-functionalized silica was prepared. The preparation experiments introduced different amounts of –CH₃ moieties to regulate the surface properties. Introduction of more –CH₃ in the –SO₂NHSO₂C₄F₉ series brought about the materials' macroscopic hydrophobicity as expected, shown by the increased contact angle; but it was not so in the –SO₂NHSO₂CF₃ series, which kept their hydrophilicity. In the application of fructose dehydration, the yields of HMF catalysed by the –C₄F₉-series catalysts were 10% higher than those by the –CF₃-series catalysts at the same level of –CH₃ introduced in 20% aqueous ethanol. This was due to their macroscopic hydrophobicity. However, the maximum amount of –CH₃ introduced in both the –C₄F₉– and –CF₃-series catalysts caused ca. 6% higher HMF yields, suggesting that the –CH₃ moiety always promoted the dehydration. It was proposed that –CH₃ changed the surface properties, even in the hydrophilic catalysts. This was confirmed by fluorescence spectrometry with pyrene as a probe molecule. An obvious enhancement of the surface nonpolarity in the introduction of a high amount of –CH₃ was shown by the band III/I ratio of the spectra (0.60–0.83). The improved nonpolarity helped to repel water, both for the –C₄F₉– and –CF₃-series catalysts. In particular, for the –C₄F₉ series, their water-repellent ability was strengthened, and the –C₄F₉ group preferably repelled the produced water away from the adjacent NH site. This could weaken HMF rehydration at the acid site. The regulation effect of –CH₃ along with the enhancement caused by –C₄F₉ thus raised the total yield of HMF to ca. 15%. The enhanced nonpolarity effect by perfluoroalkyl around the acid site should be interesting to design new solid acids with hydrophilicity–hydrophobicity balance.

中文翻译：

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二氧化硅负载的全氟烷基磺酰亚胺对催化果糖脱水的非极性作用增强

制备了-SO ₂ NHSO ₂ C ₄ F ₉ / CF _3-官能化的二氧化硅。制备实验引入了不同数量的–CH ₃部分，以调节表面性能。在–SO ₂ NHSO ₂ C ₄ F ₉系列中引入更多的–CH ₃导致了材料的宏观疏水性，如预期的那样，这是通过增加接触角来表明的。但在–SO ₂ NHSO ₂ CF _3中却不是系列，保持其亲水性。在果糖脱水应用中，在20％乙醇水溶液中引入相同水平的–CH _3时，–C ₄ F ₉系列催化剂催化的HMF产率比–CF ₃系列催化剂催化的HMF产率高10％。。这是由于它们的宏观疏水性。但是，在–C ₄ F ₉ –和–CF ₃系列催化剂中引入的–CH ₃的最大量均会导致大约_10％的残留物。HMF产率提高6％，表明–CH ₃部分始终促进脱水。有人建议–CH ₃甚至在亲水性催化剂中也改变了表面性能。通过以pyr为探针分子的荧光光谱法证实了这一点。光谱的III / I谱带比（0.60–0.83）显示了引入大量–CH ₃时表面非极性的明显增强。改进的非极性有助于排斥–C ₄ F ₉ –和–CF ₃系列催化剂的水。特别是，对于–C ₄ F ₉系列，其疏水能力得到了增强，而–C ₄ F _9系列该小组优选将产出水驱离邻近的NH位点。这可能会削弱酸性位置的HMF补液。–CH ₃的调节作用以及–C ₄ F ₉引起的增强作用因此将HMF的总收率提高到了约5％。15％。设计具有亲水性-疏水性平衡的新固体酸时，全氟烷基酸位点周围增强的非极性作用应该是令人感兴趣的。