Rai Pradeep K, Parra-Vasquez A Nicholas G, Chattopadhyay Jayanta, Pinnick Robert A, Liang Feng, Sadana Anil K, Hauge Robert H, Billups W Edward, Pasquali Matteo
Carbon Nanotechnology Laboratory, Smalley Institute for Nanoscale Science and Technology, rice University, Houston, Texas 77005, USA.
J Nanosci Nanotechnol. 2007 Oct;7(10):3378-85. doi: 10.1166/jnn.2007.835.
The manipulation and processing of single-wall carbon nanotubes (SWNTs) is limited by their poor solubility in most common solvents. Covalent sidewall functionalization of SWNTs provides an excellent route to improve their solubility. Here we have studied the relationship between sidewall functionalization and phase behavior of solutions of functionalized SWNTs (f-SWNTs) in strong acids. We use centrifugation in conjunction with UV-Vis-nlR spectroscopy to quantify the solubility of f-SWNTs in strong acids. We image the dispersions of functionalized tubes by polarized light microscopy. We find that adding butyl groups increases marginally the solubility of SWNTs in 102% sulfuric acid in the isotropic phase; adding 9-nonadecyne groups roughly doubles the solubility of SWNTs. Viscosity measurements in dilute solutions are sensitive to de-bundling. We compare the viscosity-concentration dependence of dilute pristine and f-SWNTs to assess whether and how functionalization promotes de-bundling and stabilizes the tubes. The phase behavior and rheology of these f-SWNTs parallels with that of pristine SWNTs; 9-nonadecylated SWNTs have higher solubility and should be easier to process.
单壁碳纳米管（SWNTs）在大多数常见溶剂中的溶解度较差，这限制了其操控和加工。SWNTs的共价侧壁功能化是提高其溶解度的一条极佳途径。在此，我们研究了侧壁功能化与功能化单壁碳纳米管（f-SWNTs）在强酸中的溶液相行为之间的关系。我们结合使用离心法和紫外-可见-近红外光谱来量化f-SWNTs在强酸中的溶解度。我们通过偏光显微镜对功能化碳纳米管的分散体进行成像。我们发现，添加丁基在各向同性相中使SWNTs在102%硫酸中的溶解度略有增加；添加9-十九炔基使SWNTs的溶解度大致翻倍。稀溶液中的粘度测量对解束很敏感。我们比较了稀的原始SWNTs和f-SWNTs的粘度-浓度依赖性，以评估功能化是否以及如何促进解束并使碳纳米管稳定。这些f-SWNTs的相行为和流变学与原始SWNTs的相行为和流变学相似；9-十九烷基化的SWNTs具有更高的溶解度，应该更易于加工。
