Determination of volatility of ionic liquids at the nanoscale by means of ultra-fast scanning calorimetry
Determination of volatility of ionic liquids at the nanoscale by means of ultra-fast scanning calorimetry
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DOI：
10.1039/c3cp54325k
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发表时间：
2014-01-01
影响因子：
3.3
通讯作者：
Schick, Christoph
中科院分区：
文献类型：
--
作者：
Ahrenberg, Mathias;Brinckmann, Marcel;Schick, Christoph
由于极低挥发性离子液体的蒸汽压较低，测定其汽化热具有挑战性和耗时的特点。此外，即使在蒸汽压仍然很低的温度下，这些液体也容易分解。因此，测定汽化热的传统方法仅限于低于分解温度的温度。本文提出了一种用差示快速扫描量热法测定这类液体的汽化热的新方法。我们已经使用[EMIM][NTf2]在高达750K的温度和不同的大气中开发并证明了这种方法。研究表明，即使在如此高的温度下，蒸发仍然是主要的质量损失过程。此外，由于该方法允许很高的升温速率(高达10(5)K S(-1))，因此与普通装置相比，在不显著分解离子液体的情况下，测量质量损失率的温度可以达到更高的温度。讨论了这种新的汽化热测定方法的优点和局限性，并与已有方法的结果进行了比较。
The determination of vaporization enthalpies of extremely low volatility ionic liquids is challenging and time consuming due to the low values of vapor pressure. In addition, these liquids tend to decompose even at temperatures where the vapor pressure is still low. Conventional methods for determination of vaporization enthalpies are thus limited to temperatures below the decomposition temperature. Here we present a new method for the determination of vaporization enthalpies of such liquids using differential fast scanning calorimetry. We have developed and proven this method using [EMIm][NTf2] at temperatures of up to 750 K and in different atmospheres. It was demonstrated that evaporation is still the dominating process of mass loss even at such highly elevated temperatures. In addition, since the method allows very high heating rates (up to 10(5) K s(-1)), much higher temperatures can be reached in the measurement of the mass loss rate as compared to common devices without significant decomposition of the ionic liquid. We discuss the advantages and limits of this new method of vaporization enthalpy determination and compare the results with data obtained from established methods.