The effect of cosolvents (ethanol, acetone, n-heptane) on the supercritical CO2 system were evaluated through the multi-scale molecular modeling and dissolution behavior measurement, which might improve the solvent-solvent and solvent-solute interactions and enhance the compatibility with polymer. The ab initio calculation showed that the interaction between ethanol and CO2 was the strongest one, followed by that of acetone and n-heptane. The molecular dynamics simulations indicated that ethanol significantly increased the solubility parameter of solvent, and the interaction of supercritical CO2-ethanol with PVAc chain was stronger than that of the other two at the same co-solvent content, which was helpful to improve the compatibility between PVAc and the solvent. The interaction between ethanol and CO2 was the strongest due to the bigger solubility parameter of ethanol and the obvious hydrogen bond between ethanol and CO2.The cloud point experiments confirmed that ethanol was the most effective to reduce the cloud point pressure of PVAc. The addition of cosolvent enhanced the compatibility of supercritical CO2 system with PVAc, and the solubility of PVAc in supercritical CO2-cosolvent increased with the mole fraction of cosolvent.%采用多尺度模拟和实验结合研究了乙醇、丙酮、正庚烷等共溶剂的加入对超临界二氧化碳(CO2)溶剂体系的影响,通过改善溶剂-溶剂和溶剂-溶质相互作用增强聚醋酸乙烯酯(PVAc)与CO2的相容性.量子力学从头算结果表明,3种共溶剂中乙醇与CO2的相互作用最强,丙酮次之,正庚烷最弱.分子动力学模拟也表明在相同共溶剂含量下,乙醇对溶剂体系溶解度参数的改善最为明显,超临界CO2-乙醇体系与PVAc链的相互作用更强,有助于提高PVAc与溶剂的相容性.这是由于乙醇本身的溶解度参数较大,且与CO2形成氢键作用,从而大幅增强了其与CO2的相互作用.浊点压力实验证实了共溶剂的加入增强了超临界CO2体系与PVAc的相容性,乙醇的加入对PVAc浊点压力的降低最为有效,且随着共溶剂含量的增加,PVAc在溶剂中的溶解能力增强.
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