Effects of Cationic Ammonium Gemini Surfactant on Micellization of PEO鈥揚PO鈥揚EO Triblock Copolymers in Aqueous Solution

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• 作者：Ruijuan Wang ; Yongqiang Tang ; Yilin Wang
• 刊名：Langmuir
• 出版年：2014
• 出版时间：March 4, 2014
• 年：2014
• 卷：30
• 期：8
• 页码：1957-1968
• 全文大小：638K
• 年卷期：v.30,no.8(March 4, 2014)
• ISSN：1520-5827

文摘

Effects of cationic ammonium gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12鈥?鈥?2) on the micellization of two triblock copolymers of poly(ethylene oxide)鈥損oly(propylene oxide)鈥損oly(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鈥?鈥?2 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鈥?鈥?2. The critical micelle temperature (CMT) of the two copolymers decreases as the 12鈥?鈥?2 concentration increases and the ability of 12鈥?鈥?2 in lowering the CMT of F127 is slightly stronger than that of P123. Moreover, a combination of ITC and DLS has shown that 12鈥?鈥?2 binds to the copolymers at the temperatures from 16 to 40 掳C. At the temperatures below the CMT of the copolymers, 12鈥?鈥?2 micelles bind on single copolymer chains and induce the copolymers to initiate aggregation at very low 12鈥?鈥?2 concentration. At the temperatures above the CMT of the copolymers, the interaction of 12鈥?鈥?2 with both monomeric and micellar copolymers leads to the formation of the mixed copolymer/12鈥?鈥?2 micelles, then the mixed micelles break into smaller mixed micelles, and finally free 12鈥?鈥?2 micelles form with the increase of the 12鈥?鈥?2 concentration.