Hydrophobic terminal group of surfactant initiating micellization as revealed by H-1 NMR spectroscopy
Hydrophobic terminal group of surfactant initiating micellization as revealed by H-1 NMR spectroscopy
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H-1 NMR 光谱显示表面活性剂的疏水端基引发胶束化
DOI：
10.1016/j.cclet.2017.04.013
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发表时间：
2017
影响因子：
9.1
通讯作者：
Du You-Ru
中科院分区：
文献类型：
--
作者：
Yu Gang-Jin;Chen Xiao-Ying;Mao Shi-Zhen;Liu Mai-Li;Du You-Ru
通过1H化学位移随表面活性剂浓度的变化，测定了四种常规表面活性剂的临界聚集浓度（CAC），即两种阳离子表面活性剂[十六烷基三甲基溴化铵（CTAB）和十四烷基三甲基溴化铵（TTAB）]、一种阴离子表面活性剂[十二烷基硫酸钠（SDS）]和一种非离子表面活性剂[Triton X-100（TX-100）]。结果表明，同一分子不同位置的质子的CAC值不同，末端甲基质子的CAC值最低，这表明在胶束化过程中，烷基链的端基首先聚集。对SDS中不同质子的横向弛豫时间（T2）的测量也表明，末端甲基质子首先随着浓度的增加而开始减少，这支持了上述趋势。
The critical aggregation concentration (CAC) of four with three kinds of conventional surfactants, namely, two cationic surfactants [hexadecyltrimethyl ammonium bromide (CTAB) and tetradecyltrimethyl ammonium bromide (TTAB)], one anionic surfactant [sodium dodecyl sulfate (SDS)], and a nonionic surfactant [Triton X-100 (TX-100)], were determined by variation of1H chemical shifts with surfactant concentrations. Results show that the CAC values of protons at different positions of the same molecule are different, and those of the terminal methyl protons are the lowest, respectively, which suggests that the terminal groups of the alkyl chains aggregates first during micellization. Measurement of the transverse relaxation time (T2) of different protons in SDS also show that the terminal methyl protons start to decrease with the increase in concentration first, which supports the above mentioned tendency.