月桂酰丙氨酸的胶束行为研究

Research on micelle formation of N-lauroylalanine

测定了月桂酰丙氨酸(LA)的中和点和表面张力;探究了pH、温度及离子强度对表面张力的影响,计算了LA的一些物理参数。结果表明:LA的中和点pH为7.8。在pH为7~11时,随着pH升高,LA的cmc、γcmc及Amin增加,Гmax降低;在pH为7、9时,LA溶液形成不对称形状的胶团;在pH为11时形成球形胶团。在温度为25~45℃时,cmc及γcmc随着温度的升高而降低,ΔGmic均为负值,ΔHmic均为正值,胶束化过程是自发的吸热熵驱动过程。随着NaCl浓度的升高,cmc及Гmax降低,Amin升高,γcmc变化不明显。

The point of neutralization and surface tension of N-lauroylalanine(LA)were measured.The ef⁃fects of pH,temperature and ionic intensity on surface tension were investigated,and some physical parame⁃ters of LA were calculated.The results showed that the point of neutralization pH of LA was 7.8.When pH was 7~11,cmc,γcmc and Amin of LA increased andГmax decreased with the increase of pH.When pH was 7 and 9,LA solution could form asymmetric micelles,and when pH was 11,it formed spherical micelle.When tem⁃perature was 25~45℃,cmc andγcmc decreased with the increase of temperature,ΔGmic was negative andΔHmic was positive.The micellization process was spontaneous and endothermic driven by entropy.With the in⁃crease of NaCl concentration,cmc andГmax decreased,Amin increased andγcmc did not change significantly.