Phase behavior and shear alignment in SWNT-surfactant dispersions.
Phase behavior and shear alignment in SWNT-surfactant dispersions.
复制标题
SWNT-表面活性剂分散体中的相行为和剪切排列。
DOI：
10.1002/smll.200800082
复制
发表时间：
2008
期刊：
影响因子：
13.3
通讯作者：
O. Regev
中科院分区：
文献类型：
--
作者：
Einat Nativ‐Roth;R. Yerushalmi‐Rozen;O. Regev
在室温下研究了单壁碳纳米管（SWNT）对阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）在水溶液中相行为的影响。小角 X 射线散射 (SAXS) 和低温透射电子显微镜 (cryo-TEM) 用于表征本体分散体和纳米薄膜。其他碳质添加剂（富勒烯、多壁碳纳米管和炭黑）用作参考系统。研究发现，碳质添加剂（不包括富勒烯）在中等表面活性剂浓度（低于天然表面活性剂的液晶区域）的分散体会在其他均匀的 CTAB 溶液中引起分层和宏观相分离。观察到两个 CTAB 浓度相似的共存液相，碳质物质位于下相内。在高 CTAB 浓度（液晶区域）下，发现单壁碳纳米管会融入有序的溶致液晶相，同时保留天然的 d 间距。在外部剪切下对中等表面活性剂浓度的纳米薄膜进行研究，揭示了在微量单壁碳纳米管存在下的剪切诱导结构 (SIS)。发现这种效应是单壁碳纳米管所独有的，并且不会出现在其他碳质添加剂的分散体中。
The effect of single-walled carbon nanotubes (SWNT) on the phase behavior of the cationic surfactant cetyltrimethylammonium bromide (CTAB) in aqueous solutions is investigated at room temperature. Small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM) are used for characterization of bulk dispersions and nanometrically thin films. Additional carbonaceous additives (fullerenes, multi-walled carbon nanotubes, and carbon black) serve as reference systems. It is found that dispersions of carbonaceous additive (excluding fullerenes) at intermediate surfactant concentrations (below the liquid-crystalline region of the native surfactant) induce demixing and macroscopic phase separation in otherwise homogeneous solutions of CTAB. Two coexisting liquid phases of similar CTAB concentrations are observed, with the carbonaceous species residing within the lower phase. At high CTAB concentrations (liquid-crystal region) the SWNTs are found to incorporate into the ordered lyotropic liquid-crystalline phase while preserving the native d-spacing. Investigation of nanometrically thin films at intermediate surfactant concentrations under external shear reveals shear-induced structure (SIS) in the presence of minute amounts of SWNTs. The effect is found to be exclusive to SWNT and does not occur in dispersions of other carbonaceous additives.
DOI：
10.1016/b978-0-12-221820-0.x5000-x
发表时间：
1996
期刊：
--
影响因子：
--
作者：
L. B. Ebert
通讯作者：
L. B. Ebert