超临界CO_(2)中烷基聚醚的溶解规律研究

Study on solubility of alkyl polyether in supercritical carbon dioxide

通过浊点压力实验考察了温度、聚合度、烷基链长度以及烷基聚醚含量对烷基聚醚在超临界CO_(2)中溶解度的影响,采用分子动力学模拟计算分析了烷基聚醚分子间相互作用、烷基聚醚和CO_(2)之间的相互作用,并探索了烷基聚醚与CO_(2)的微观相溶规律。实验结果表明,温度升高,烷基聚醚在超临界CO_(2)中的溶解度减小,烷基聚醚与CO_(2)之间的亲和性降低;在分子中引入聚氧丙烯基团有利于提高烷基聚醚在超临界CO_(2)中的溶解度,但存在最佳聚合度范围。十二烷基聚氧丙烯醚比十二烷基聚氧乙烯醚的溶解度参数小,分子间相互作用更弱,且在超临界CO_(2)中更分散,与CO_(2)的相互作用能更大,使其与CO_(2)亲和性更强,浊点压力更低,溶解度更好。

The effects of temperature,polymerization degree,alkyl chain length and alkyl polyether content on the solubility of alkyl polyethers in supercritical CO_(2) were investigated by cloud point pressure experiment.Molecular dynamic simulation was used to calculate and analyzed the intermolecular interaction of alkyl polyethers and the interaction between alkyl polyethers and CO_(2),which explored microscopic dissolution mechanism of alkyl polyethers and CO_(2).The experimental results show that with the increase of temperature,the solubility of alkyl polyethers in supercritical CO_(2) decreases,and the affinity between alkyl polyethers and CO_(2) decreases.The introduction of polyoxypropylene groups into the molecular is beneficial to improve the solubility of alkyl polyethers in supercritical CO_(2),but there is an optimal range of polymerization degree.Dodecyl polyoxypropylene ether(C12PO3)has a lower solubility parameter than dodecyl polyoxyethylene ether,which makes the intermolecular interaction weaker.Moreover,C_(12)PO_(3) is more dispersed in supercritical CO_(2) and has higher interaction energy with CO_(2),resulting in better affinity between C_(12)PO_(3) and CO_(2),lower cloud point pressure and better solubility.