一种新的计算Langmuir单层膜中二元聚集参数的数学模型及实验研究

摘要

建立了一种新的对Langmuir膜中二元组分聚集有关参数定量计算的数学模型.该模型能实现对平衡常数、二聚物的平均分子面积、未聚集组分的平均分子面积、发生聚集的物质占总物质的比例等参数的计算,并首次导出两种组分中发生聚集的物质占总物质的比例与两种组分比例的函数关系.选用硬脂酸(stearic acid,SA)和二棕榈酸磷酸酰胆碱(dipalmitoyl phosphatidylcholine,DPPC)为原料制成Langmuir膜,对模型进行实验验证,结果表明SA与DPPC的平均分子面积分别为24.0(A)2/molecule和63.7 (A)2/molecule,其二聚物的平均分子面积为81.3 (A)2/molecule,室温下聚集常数为1.86× 107 m2/mol.并得出SA所占比例约为49.73％时,发生聚集的组分的物质的量与膜中加入组分的总物质的量的比值最大,约有84.96％的分子发生了聚集反应.%A new mathematical model to measure the parameters about the formation of binary complexes in the Langmuir monolayer film was developed.Some important parameters such as the stability constant,the mean molecular areas of binary complexes and unpolymerized molecules,the proportion of molecules which formed complexes and so on could be got,through which a function about the relationship between the proportion of the amount of the molecules which had polymerized to the total amount of the molecules in the Langmuir monolayer,and the ratio of the amounts of two different components were derived for the first time.Dipalmitoylphosphatidylcholine (DPPC) and stearic acid (SA) were selected as materials to make Langmuir films to validate the new method.Following results were got:mean molecular areas of SA and DPPC are 24.0 (A)2/molecule and 63.7 (A)2/molecule respectively,the mean molecular area of dimers is 81.3 (A)2/molecule,the stability constant at room temperature is 1.86×107 m2/mol,and the proportion of the molecules which have polymerized reaches its highest value-about 84.96％ of the total molecules in the Langmuir monolayer when the proportion of the amount of SA is 49.73％.