Low-temperature heat capacity of room-temperature ionic liquid, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.
Low-temperature heat capacity of room-temperature ionic liquid, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.
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DOI：
10.1021/jp0618330
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发表时间：
2006-06
期刊：
影响因子：
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通讯作者：
Yoshitaka Shimizu;Yoko Ohte;Y. Yamamura;Kazuya Saito;T. Atake
中科院分区：
文献类型：
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作者：
Yoshitaka Shimizu;Yoko Ohte;Y. Yamamura;Kazuya Saito;T. Atake
采用绝热量热法测定了室温离子液体（RTIL）1-己基-3-甲基咪唑双（三氟甲基磺酰基）酰亚胺（1-hexyl-3-methylimidazolium bis（trifluromethylsulfonyl）imide）在5 ~ 310 K范围内的液态、稳定晶体和液体淬冷玻璃的热容。在298.15 K时，IUPAC项目确定的液体热容为（631.6 +/- 0.5）J K（-1）mol（-1）。在T（fus）= 272.10 K时观察到稳定晶相的熔化，熔化焓和熵分别为28.34 kJ mol（-1）和104.2 J K（-1）mol（-1）。通过分步熔融法估计样品的纯度为99.83mol%。在T（g）约为183 K时，该体系发生了玻璃化转变，与经验公式T（g）约为（2）/（3）T（fus）相一致。液体淬火玻璃的热容大于晶体整体的热容。在最低温度区，两者的热容量差在6 K附近达到最大值，在15 K附近达到最小值，此时玻璃的热容量比晶体的热容量小一些。
Heat capacities of liquid, stable crystal, and liquid-quenched glass of a room-temperature ionic liquid (RTIL), 1-hexyl-3-methylimidazolium bis(trifluromethylsulfonyl)imide were measured between 5 and 310 K by adiabatic calorimetry. Heat capacity of the liquid at 298.15 K was determined for an IUPAC project as (631.6 +/- 0.5) J K(-1) mol(-1). Fusion was observed at T(fus) = 272.10 K for the stable crystalline phase, with enthalpy and entropy of fusion of 28.34 kJ mol(-1) and 104.2 J K(-1) mol(-1), respectively. The purity of the sample was estimated as 99.83 mol % by the fractional melting method. The liquid could be supercooled easily and the glass transition was observed around T(g) approximately 183 K, which was in agreement with the empirical relation, T(g) approximately ((2)/(3)) T(fus). The heat capacity of the liquid-quenched glass was larger than that of the crystal as a whole. In the lowest temperature region, however, the difference between the two showed a maximum around 6 K and a minimum around 15 K, at which the heat capacity of the glass was a little smaller than that of crystal.