共 44 条
Thermodynamics of molecular self-assembly of cationic gemini and related double chain surfactants in aqueous solution
被引:136
作者:
Bai, GY
Wang, JB
Yan, HK
[1
]
Li, ZX
Thomas, RK
机构:
[1] Chinese Acad Sci, Inst Chem, Ctr Mol Sci, Beijing 100080, Peoples R China
[2] Univ Oxford, Phys & Theoret Chem Lab, Oxford OX1 3QZ, England
来源:
JOURNAL OF PHYSICAL CHEMISTRY B
|
2001年
/
105卷
/
15期
关键词:
D O I:
10.1021/jp0043017
中图分类号:
O64 [物理化学(理论化学)、化学物理学];
学科分类号:
070304 ;
081704 ;
摘要:
Microcalorimetric measurements have been made on the series of gemini surfactants [CMH2M+1(CH3)(2)N-(CH2)(S)N(CH3)(2)CMH2M+1] Br-2, designated CMCSCMBr2, where M and S indicate the numbers of carbons in the side chains and spacer respectively, for M = 12 and S = 3, 4, 6, 8, 10, 12. For comparison, parallel measurements have been made on the series of double-chain, singly charged surfactants dodecyldimethyl-alkylammoninm bromides, designated as C12CNBr With N = 1; 2, 4, 6, 8, 10, 12, where N is the number of carbons in the secondary alkyl chain. The choice of this second series was to compare each CMCSCMBr2 with its nearest equivalent monomer C12CS/2Br The values of the critical micelle concentrations (cmc) were found to be in good agreement with other measurements, showing a maximum at S = 4-6 for the geminis and a nonlinear variation with chain length for the C12CNBr series. For both series of surfactants, the enthalpies of micellization, DeltaH(mic), are all exothermic and show a marked minimum in magnitude at S = 4-6 or N = 4-6. The variation of DeltaH(mic) and DeltaS(mic) across both series shows that the balance between enthalpic and entropic contributions to the process of micellization changes substantially with S or N.
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页码:3105 / 3108
页数:4
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