假設i ) 離子液體中不同的離子狀態，在平衡時彼此的交換速率太快，以致於無法以核磁共振的實驗來各個區別。以及 ii) 量測到的擴散速率，可視為所有可能的狀態化合物擴散速率的總和平均。溶劑與陰離子擴散係數比值─Ds/D-，或者與陽離子擴散比值─Ds/D+，在任一特定離子液體/共溶劑內提供了下述兩點物理意義：即一、相對於自由離子，離子液體中實際的陰離子聚合度(ASS-)大於陽離子聚合度(ASS+)，二、ASS- 隨共溶劑比率增大而下降程度也是大於ASS+。本篇以離子液體BMIPF6在共溶劑AN莫耳分率為0.2，室溫300K時，其ASS-由3.64降至2.05，ASS+由2.71降至1.57，可以證明上述兩點。其他共溶劑(DMF、DMSO、PC)陰陽離子聚合度以及聚合度下降幅度，不若AN大，但也都符合上述兩點。
本實驗證明室溫下帶負電簇合物的形成在AN中最大，當x=0.2時ASS- = 3.64，其次DMF( 2.45)、DMSO(1.83)，最小PC (1.80)。同樣地帶正電簇合物的形成順序為AN (2.71)、DMF (1.76)、DMSO (1.66)、PC (1.43)。而由ASS- / ASS+ = HAP，可得知PC的HAP為四種溶劑中最低，也就是自由陽離子多於自由陰離子的程度，以PC最大。亦可得知含C=O的共溶劑與BMIPF6作用力優於含C≡N，因前者有較小的ASS值。

Assuming that i) various ionic states in ionic liquids (IL) are in equilibrium with exchange rates too high to be distinguished by NMR experiments and ii) the overall response of measured diffusivity is viewed as the sum of weighted responses of diffusivity of all possible components. Then, the ratio of solvent diffusivity to anion diffusivity, Ds/D- or to cation diffusivity, Ds/D+, in a specified IL/co-solvent suggests two physical meaning: i) compared to free-ion, the relative association degrees of anion-containing components (ASS-) were larger than the relative association degrees of cation-containing components (ASS+); ii) the decrease for ASS- were more than for ASS+ with the increase of molar fraction of co-solvent. It was found that when 1-butyl-3- methylimidazolium hexafluorophosphate (BMI-PF6) was mixed with acetonitrile (AN) in a the molar fraction (X) of 0.2 at 300K, the ASS- was from 3.64 to 2.05 and ASS+ was from 2.71 to 1.57. These results were in consistent with the above observations. And when mixed with other co-solvents, such as DMF, DMSO, and PC, it also showed the same results with smaller degrees of association for both ions.
This study has proven that anion-association components were formed more easily in AN than in other co-solvents. It was found that with X = 0.2 in respective co-solvent of AN, DMF, DMSO and PC, the ASS- was 3.64, 2.45, 1.83, and 1.80; whileas it was 2.71, 1.76, 1.66, and 1.43, respective. It was found that the above four co-solvents resulted in more free cations than anions. Especially, it was more obvious when PC was as the co-solvent. And with PC as the co-solvent , the HAP (i.e. ASS- / ASS+ ) is the smallest (1.27). This study also showed that co-solvent containing the moiety of C=O showed better interactions with BMI-PF6 than that containing the moiety of C≡N.

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