Huang Xu, Wang Yilin, Dong Chuchuan, Shen Hsin-Hui, Thomas R K
Key Laboratory of Colloid and Interface Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, People's Republic of China.
J Colloid Interface Sci. 2008 Sep 1;325(1):114-21. doi: 10.1016/j.jcis.2008.05.043. Epub 2008 May 29.
The adsorbed layers of N,N,N-trimethyl-10-(4-nitrophenoxy)decylammonium bromide (PhiC(10)TAB) and N,N,N('),N(')-tetramethyl-N,N(')-bis[10-(4-nitrophenoxy)decyl]-1,6-hexanediammonium dibromide [(PhiC(10))(2)C(6)] at the air/water interface have been studied by neutron reflection. The coverage of the surfactants was obtained over the concentration range from critical micelle concentration (CMC) to CMC/100. The area per PhiC(10)TAB molecule changes from 50+/-3 to 390+/-60 A(2) over this concentration range and the area per (PhiC(10))(2)C(6) molecule changes from 139+/-3 to 288+/-10 A(2). The overall thicknesses (single uniform layer) of the surfactant layers at CMC are about 19 and 16 A for PhiC(10)TAB and (PhiC(10))(2)C(6) respectively. The distributions of the C(10) chains show that the chains of both surfactants are tilted away from surface normal, with the tilt increasing in the outer part of the layer. The distribution of C(10) chains in (PhiC(10))(2)C(6) is narrower than that in PhiC(10)TAB, indicating that the alkyl chains of (PhiC(10))(2)C(6) are more tilted. For both surfactants, the broad nitrophenoxy distribution may indicate significant positional disorder of the nitrophenoxy groups along the surface normal direction and their intermixing with alkyl chains in the adsorbed layer.
通过中子反射研究了N,N,N-三甲基-10-(4-硝基苯氧基)癸基溴化铵（PhiC(10)TAB）和N,N,N',N'-四甲基-N,N'-双[10-(4-硝基苯氧基)癸基]-1,6-己二铵二溴化物[(PhiC(10))(2)C(6)]在空气/水界面的吸附层。在从临界胶束浓度（CMC）到CMC/100的浓度范围内获得了表面活性剂的覆盖度。在此浓度范围内，每个PhiC(10)TAB分子的面积从50±3 Ų变化到390±60 Ų，每个(PhiC(10))(2)C(6)分子的面积从139±3 Ų变化到288±10 Ų。在CMC时，PhiC(10)TAB和(PhiC(10))(2)C(6)表面活性剂层的总厚度（单一均匀层）分别约为19 Å和16 Å。C(10)链的分布表明，两种表面活性剂的链都倾斜远离表面法线，且在层的外部倾斜度增加。(PhiC(10))(2)C(6)中C(10)链的分布比PhiC(10)TAB中的窄，这表明(PhiC(10))(2)C(6)的烷基链倾斜度更大。对于两种表面活性剂，宽的硝基苯氧基分布可能表明硝基苯氧基基团沿表面法线方向存在显著的位置无序，并且它们在吸附层中与烷基链相互混合。
