Institute of Advanced Materials and Processes (ZMP), University of Erlangen-Nuremberg, Dr. Mack Strasse 81, 90762 Fuerth, Germany.
Chemistry. 2010 Nov 22;16(44):13176-84. doi: 10.1002/chem.200903461.
We report on the extensive characterization of single-walled carbon nanotubes (SWCNTs) dispersed in a variety of surfactants, such as sodium dodecyl benzene sulfonate (SDBS), sodium cholate (SC), and three synthesized perylene-based surfactants, by using differential sedimentation in H(2)O and D(2)O. Multidimensional evaluation of the absorption profiles over radius, wavelength, and time allows the determination of the anhydrous specific volumes of the SWCNT-surfactant complexes as well as the concentration of the surfactant reservoir in free micelles with very slow sedimentation coefficients (<1 Svedberg). Among the perylene bisimide surfactants, the smallest derivative is densely adsorbed on the nanotube backbone with an anhydrous specific volume significantly above that of SC or SDBS. Bulky Newkome dendritic groups on one or both ends of the perylene moiety gradually reduce the adsorption density, in accord with the absolute adsorption between 0.66 and 1.7 mmol surfactant per gram SWCNTs. Furthermore, hydrodynamic analysis reveals that SDBS favors the "tails-on" configuration. The distribution of sedimentation coefficients of SWCNTs prepared by high-pressure carbon monoxide decomposition (HiPco) is broader and shifted to faster sedimentation than those prepared by using cobalt-molybdenum catalysis (CoMoCAT), which reflects the polydispersity in diameter and length.
我们报告了在各种表面活性剂（如十二烷基苯磺酸钠（SDBS）、胆酸钠（SC）和三种合成的苝基表面活性剂）中分散的单壁碳纳米管（SWCNT）的广泛特性，方法是使用 H（2）O 和 D（2）O 中的差异沉降。对半径、波长和时间的吸收曲线进行多维评估，可确定 SWCNT-表面活性剂复合物的无水比容以及具有非常缓慢沉降系数（<1 Svedberg）的游离胶束中表面活性剂库的浓度。在苝二酰亚胺表面活性剂中，最小的衍生物紧密吸附在纳米管主链上，无水比容显著高于 SC 或 SDBS。一端或两端的庞大 Newkome 树枝状基团逐渐降低吸附密度，与 0.66 至 1.7 mmol 每克 SWCNTs 的表面活性剂之间的绝对吸附一致。此外，流体力学分析表明 SDBS 有利于“尾部朝上”的构象。通过高压一氧化碳分解（HiPco）制备的 SWCNT 的沉降系数分布更宽，向更快的沉降方向移动，而通过使用钴-钼催化（CoMoCAT）制备的 SWCNT 的沉降系数分布则更窄，这反映了直径和长度的多分散性。
