Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), College of Chemistry and Chemical Engineering , Hunan Normal University , Changsha 410081 , China.
J Phys Chem B. 2019 Sep 26;123(38):8140-8153. doi: 10.1021/acs.jpcb.9b05982. Epub 2019 Sep 16.
To explore the role of matching water affinities between the oppositely charged headgroups, the micellization of cetyltrimethylammonium bromide (CTABr)/sodium dodecanoate (NaL) mixed system and the CTABr/sodium dodecylsulfonate (NaAS) mixed system has been investigated by the surface tension method and molecular dynamic (MD) simulation. In comparison with the CTABr/NaL system, the CTABr/NaAS system shows stronger micelle formation ability, smaller critical micelle concentration (cmc), and stronger synergistic effect arising from the higher degree of matching water affinities between the headgroups CTA and AS. To explore the role of matching water affinities between the oppositely charged constituent counterions, the micellization of CTAX/YL mixed systems with various counterions has been investigated. The higher degree of matching water affinities between counterions X and Y and the higher degree of mismatching water affinities between headgroups and counterions are unfavorable to the screening effect of counterions on the electrostatic attraction between headgroups CTA and L, leading to stronger micelle formation ability and smaller cmc and vice versa. MD simulation results also indicate that, for the mixed micellization of cationic/anionic surfactants, the role of matching water affinities between oppositely charged headgroups is more important than that between oppositely charged constituent counterions.
为了探究相反电荷头基之间水亲和力匹配的作用，通过表面张力法和分子动力学（MD）模拟研究了十六烷基三甲基溴化铵（CTABr）/十二烷酸钠（NaL）混合体系和 CTABr/十二烷基磺酸钠（NaAS）混合体系的胶束化行为。与 CTABr/NaL 体系相比，CTABr/NaAS 体系具有更强的胶束形成能力、更小的临界胶束浓度（cmc）和更强的协同效应，这归因于头基 CTA 和 AS 之间更高的水亲和力匹配程度。为了探究相反电荷组成离子之间水亲和力匹配的作用，研究了具有不同离子的 CTAX/YL 混合体系的胶束化行为。离子 X 和 Y 之间更高的水亲和力匹配程度以及头基和离子之间更高的水亲和力不匹配程度不利于离子对 CTA 和 L 之间静电引力的屏蔽效应，导致更强的胶束形成能力和更小的 cmc，反之亦然。MD 模拟结果还表明，对于阳离子/阴离子表面活性剂的混合胶束化，相反电荷头基之间水亲和力匹配的作用比相反电荷组成离子之间的作用更重要。
