六氟化硫替代气体绝缘强度的官能团加和理论方法

Group Additivity Theoretical Model for the Prediction of Dielectric Strengths of the Alternative Gases to SF_(6)

绝缘强度是设计与发现新型SF6替代气体的关键参数,预测未知气体的绝缘强度通常采用基于量子化学计算建立的构效关系模型,计算过程复杂、误差大、且无法正确描述具有特殊化学键的气体分子.为了能够直观反映绝缘强度随结构的变化规律,提出了官能团加和方法,将分子结构分解为独立的官能团,在一级近似下,将优化后的官能团绝缘强度直接加和,即可获得气体的绝缘强度.与65种已知气体的实验绝缘强度对比,官能团加和方法计算的绝缘强度与实验值相吻合,平均绝对与相对偏差分别为0.0656与6.28%,理论预测值与实验值的相关系数达到0.9879,优于构效关系模型方法.研究结果表明,引入不饱和键或形成环结构,同时避免孤立的CHx,CF等基团,而用CF3,OCF3,SCF3等基团取代,则有利于获得绝缘性能优异的气体分子.

Dielectric strength is one of the most parameters for the design and discovery of novel eco-friendly replacement gases for SF6.Various structure-activity relationship models had been widely used to predict the dielectric strength on the basis of the quantum chemistry calculated descriptors,which are computationally demanding and usually involve significant uncertainties and incapability of treating some specific compounds.In order to predict the dielectric strength of a gas straightforwardly,group additivity method was proposed in this work.Within the first-order approximation,the direct summation of the optimized individual contributions of the functional groups gives the overall dielectric strength.In comparison with a total of 65 insulating gases,the agreement between group additivity and experimental data is excellent.The mean absolute and relative deviations are 0.0656 and 6.28%,respectively.The correlation coefficient between theory and experiment is 0.9879,which are all superior to the structure-activity relationship models.The result reveals that inducing the unsaturated group or cyclic moiety and substituting the isolated CHx and CF by CF3,OCF3,and SCF3 is efficient to improve the dielectric strength.