Acta Chimica Sinica ›› 2014, Vol. 72 ›› Issue (6): 673-681.DOI: 10.6023/A14020088 Previous Articles     Next Articles

Article

支链醇对Gemini表面活性剂表面活性和胶束化行为的影响

唐永强, 朱琳一, 韩玉淳, 王毅琳   

  1. 中国科学院化学研究所胶体界面与化学热力学实验室 北京 100190
  • 收稿日期:2014-02-19 出版日期:2014-06-14 发布日期:2014-04-29
  • 通讯作者: 王毅琳 E-mail:yilinwang@iccas.ac.cn
  • 基金资助:

    项目受国家自然科学基金(Nos.21025313,21021003)资助.

Effects of Branched-Chain Alcohols on Surface Activity and Micellization of Gemini Surfactants

Tang Yongqiang, Zhu Linyi, Han Yuchun, Wang Yilin   

  1. Key Laboratory of Colloid and Interface Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190
  • Received:2014-02-19 Online:2014-06-14 Published:2014-04-29
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Nos.21025313, 21021003).

Gemini surfactants are a kind of novel and efficient surfactants and alcohols are one of the most widely used additives to surfactant products in industries and daily life.Understanding the effects of alcohols on surface activities and micellization of gemini surfactants will promote the applications of gemini surfactants.Effects of linear-chain alcohol (1-pentanol) and branched-chain alcohols (2-hexanol and 3-heptanol) with the same main chain as 1-pentanol on the surface activity and micellization of cationic ammonium gemini surfactants C12CSC12Br2 (S=2, 4, 6, 8, 10, 12) in aqueous solution have been investigated by surface tension, electrical conductivity, isothermal titration microcalorimetry (ITC), cryogenic transmission electron microscopy (Cryo-TEM), and NMR techniques.The branched-chain alcohols have not shown obvious effects on the critical micelle concentration of surfactants (CMC), the size and the morphology of micelles due to loose microstructure and weak interactions between the alcohols and the gemini surfactant molecules.However, the addition of branched-chain alcohols greatly decreases the surface tension of surfactants and the surface tension decreases with the increase of the branching factor of the alcohols.In addition, the surfactant concentration required to reduce the surface tension of the solvent by 20 mN/m (C20) and the surface tension values of the surfactants at CMC (γCMC) decrease obviously with the increment of the branching factor of the alcohols at a fixed alcohol concentration due to the increase of the hydrophobic chain density at the air/solution interface.The results suggest that the branched-chain alcohols influence the self-assembly of surfactants more obviously at the air/solution interface than in micelles.Moreover, there is a second critical concentration in the surface tension curves of C12C10C12Br2 and C12C12C12Br2 with a longer spacer, indicating that the hydrophobic chains of these gemini surfactants are not packed tightly even above CMC due to the flexibility of their spacers and low CMC, and are packed more tightly with the increase of the surfactant concentration.The addition of alcohols decreases the second critical concentration remarkably with the increase of their branching factor, which means that the branched alcohols have a more obvious effect on the surface activity of gemini surfactants with a longer spacer.This work helps us to understand the effects of branched-chain alcohols on the self-assembly of gemini surfactants at air/solution interface and in bulk solution, and may provide some guidance on how to choose alcohols to adjust surface activities and micellization of gemini surfactants.

Key words: Gemini surfactant, branched-chain alcohol, surface activity, micellization