C.I.分散棕19在超临界CO2及水中溶解性的分子动力学模拟

为探究分散染料在超临界CO₂和水中各自染色条件下的溶解性,基于分子动力学模拟,采用热力学积分方法分别计算了C.I.分散棕19在2种溶剂中的溶解自由能和结合自由能,并采用平均非键相互作用方法分析了C.I.分散棕19染料分子与2种溶剂分子间的弱相互作用类型及稳定性。模拟结果表明:C.I.分散棕19染料分子在超临界CO₂(24 MPa,130 ℃)和水(0.25 MPa,130 ℃)中的自由能绝对值均较小且相差不大,但其在超临界CO₂中的溶解自由能绝对值稍小,结合自由能绝对值稍大;C.I.分散棕19染料分子与2种溶剂分子间均只存在较弱且不稳定的范德华色散作用,但其与超临界CO₂分子间的弱相互作用相对于水更不稳定。

Molecular dynamics simulation of solubility of C.I. Disperse Brown 19 in supercritical CO2 and water

In order to explore the solubility differences of disperse dyes in supercritical CO₂ and water under their dyeing conditions, the solvation free energy and the binding free energy of C.I. Disperse Brown 19 in these two solvents were syudied, based on the molecular dynamics simulation, using thermodynamic integration method respectively, and the weak interaction between dye molecules and solvent molecules was examined by average noncovalent interaction method. The results showed that the absolute values of free energy of C.I. Disperse Brown 19 dye molecules in supercritical CO₂ (24 MPa, 130 ℃) and water (0.25 MPa, 130 ℃) were small, whereas the absolute value of solvation free energy in supercritical CO₂ was slightly less than that in water, and the absolute value of binding free energy was slightly greater than in water. The interactions (van der Waals force) between C.I. Disperse Brown 19 dye molecules and supercritical CO₂ molecules and water molecules were both weak and unstable, and,the interactions between the dye molecule and the supercritical CO₂ molecules were more unstable than that with water molecules.