Department of Applied chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
J Chem Phys. 2010 Aug 21;133(7):074511. doi: 10.1063/1.3469772.
Free energy of transfer, DeltaG(w-->m), from water phase to a sodium dodecyl sulfate (SDS) micelle core has been calculated for a series of hydrophobic solutes originally immiscible with water by thermodynamic integration method combined with molecular dynamics calculations. The calculated free energy of transfer is in good correspondence to the experiment as well as the theoretical free energy of transfer. The calculated DeltaG(w-->m)'s are all negative, implying that the alkane molecules are more stable in the micelle than in the water phase. It decreases almost linearly as a function of the number of carbon atoms of the alkanes longer than methane with a decrement of 3.3 kJ mol(-1) per one methylene group. The calculated free energy of transfer indicates that, for example, at the micelle concentration of 50 CMC (critical micelle concentration), about only 1 of 6 micelles or 1 of 32 000 micelles does not contain a solute methane or n-octane molecule, respectively.
已通过热力学积分法结合分子动力学计算，为一系列最初与水不混溶的疏水分子计算了从水相向十二烷基硫酸钠（SDS）胶束核心的转移自由能ΔG(w→m)。计算出的自由能转移与实验以及理论自由能转移非常吻合。计算出的ΔG(w→m)均为负值，这意味着烷烃分子在胶束中比在水中更稳定。对于甲烷以上的长链烷烃，它几乎呈线性下降，每个亚甲基组减少 3.3 kJ/mol。计算出的自由能转移表明，例如，在胶束浓度为 50 CMC（临界胶束浓度）时，约有 1/6 的胶束或 1/32000 的胶束不含溶质甲烷或正辛烷分子。
