Key Laboratory of Colloid and Interface Science, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
Langmuir. 2014 Mar 4;30(8):1957-68. doi: 10.1021/la500025k. Epub 2014 Feb 21.
Effects of cationic ammonium gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) on the micellization of two triblock copolymers of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), F127 (EO97PO69EO97) and P123 (EO20PO70EO20), have been studied in aqueous solution by differential scanning calorimetry (DSC), dynamic light scattering (DLS), isothermal titration calorimetry (ITC), and NMR techniques. Compared with traditional single-chain ionic surfactants, 12-6-12 has a stronger ability of lowering the CMT of the copolymers, which should be attributed to the stronger aggregation ability and lower critical micelle concentration of 12-6-12. The critical micelle temperature (CMT) of the two copolymers decreases as the 12-6-12 concentration increases and the ability of 12-6-12 in lowering the CMT of F127 is slightly stronger than that of P123. Moreover, a combination of ITC and DLS has shown that 12-6-12 binds to the copolymers at the temperatures from 16 to 40 °C. At the temperatures below the CMT of the copolymers, 12-6-12 micelles bind on single copolymer chains and induce the copolymers to initiate aggregation at very low 12-6-12 concentration. At the temperatures above the CMT of the copolymers, the interaction of 12-6-12 with both monomeric and micellar copolymers leads to the formation of the mixed copolymer/12-6-12 micelles, then the mixed micelles break into smaller mixed micelles, and finally free 12-6-12 micelles form with the increase of the 12-6-12 concentration.
阳离子双铵Gemini 表面活性剂己撑-1,6-双（十二烷基二甲基溴化铵）（12-6-12）对聚（环氧乙烷）-聚（环氧丙烷）-聚（环氧乙烷）两嵌段共聚物 F127（EO97PO69EO97）和 P123（EO20PO70EO20）在水溶液中的胶束化的影响已通过差示扫描量热法（DSC）、动态光散射（DLS）、等温滴定量热法（ITC）和 NMR 技术进行了研究。与传统的单链离子表面活性剂相比，12-6-12 具有更强的降低共聚物 CMT 的能力，这归因于 12-6-12 更强的聚集能力和更低的临界胶束浓度。两种共聚物的临界胶束温度（CMT）随 12-6-12 浓度的增加而降低，12-6-12 降低 F127 的 CMT 的能力略强于 P123。此外，ITC 和 DLS 的组合表明，12-6-12 在 16 至 40°C 的温度下与共聚物结合。在共聚物 CMT 以下的温度下，12-6-12 胶束结合在单链共聚物上，并在非常低的 12-6-12 浓度下诱导共聚物引发聚集。在共聚物 CMT 以上的温度下，12-6-12 与单体和胶束共聚物的相互作用导致形成混合共聚物/12-6-12 胶束，然后混合胶束分裂成更小的混合胶束，最后随着 12-6-12 浓度的增加形成游离的 12-6-12 胶束。
