2.2 f-T-P model
In this work, the f-T-P models are established to describe the
relationship of properties (density, viscosity and thermal conductivity)
with temperature and pressure. Thef-T-P (ρ-T-P , η-T-P , λ-T-P ) model shown as
Eq. (1) was used at present for this study. The fitting parametersα , β , γ and χ , used to calculate the
density, viscosity and thermal conductivity of ILs are given in
Supporting Information Figures S1~ S3.
In structure-property relationship, α is related to the
structures of ILs and the parameters β , γ and χ are
obtained by two methods: (1) β , γ and χ are set as
constants for all ILs; (2) β , γ and χ are variables
related to the molecular structure. To compare these two approaches, the
density, viscosity and thermal conductivity samples with multiple data
points are fitted using Eq. (1) by the above two methods. The calculated
results are depicted in Figures 1-3. It can be seen that the second
method results in Figure 1 (b), Figure 2 (b) and Figure 3 (b) are better
than the first method results in Figure 1 (a), Figure 2 (a) and Figure 3
(a). The correlations between the calculated and experimental values for
each sample using the second method are presented in the supporting
information. Compared with the first method, the average absolute
relative deviation (AARD ) of the second method reduced by 76 %,
79 % and 70 % for ρ , η and λ , respectively.
Accordingly, the above calculation results demonstrated that β ,γ and χ adjusted by the molecular structures are necessary
and efficient.