Liao Kang-Shyang, Wan Albert, Batteas James D, Bergbreiter David E
Department of Chemistry, Texas A&M University, College Station, TX 77842-3012, USA.
Langmuir. 2008 Apr 15;24(8):4245-53. doi: 10.1021/la703730b. Epub 2008 Mar 7.
A convenient and simple route to functionalized multiwall carbon nanotubes (MWNTs) using the reaction of the amine (NH) groups of polyethyleneimine (PEI) with MWNTs in N,N-dimethylformamide (DMF) at 50 degrees C is described. The product functionalized MWNTs (MWNT-NH-PEI) contain 6-8% by weight PEI based on elemental analysis, thermal gravimetric analysis, and titration. The products form stable emulsions in water below pH 9 and can be derivatized to form alkylated MWNTs that are dispersible in organic media. Such MWNT-NH-PEI nanoparticles can also be used in covalent or ionic layer-by-layer assembly to form nanocomposite thin films on functionalized polyethylene (PE) films and powders. Such nanocomposite films were analyzed by contact angle analysis, atomic force microscopy (AFM), and confocal Raman microscopy. These analyses show that these superhydrophilic surfaces have micro/nanoroughness with a roughly uniform distribution of MWNT nanoparticles. Superhydrophobic PE films can be formed either from ionic layer-by-layer self-assembly of MWNT-NH-PEIs and poly(acrylic acid) or from covalent layer-by-layer self-assembly of MWNT-NH-PEIs and Gantrez if the final graft is acrylated with a mixed anhydride prepared from ethyl chloroformate and octadecanoic acid. The resulting octadecylated surface produced by five covalent layer-by-layer deposition steps has a water contact angle of 165 degrees and a sliding angle of less than 5 degrees. The corresponding surface produced by five ionic layer-by-layer deposition steps has a water contact angle of 155 degrees but exhibits water pinning. The ionically assembled nanocomposite graft is labile under acidic conditions. The covalently assembled graft is more chemically robust.
描述了一种便捷且简单的方法来制备功能化多壁碳纳米管（MWNTs），即利用聚乙烯亚胺（PEI）的胺基（NH）在50℃下于N，N - 二甲基甲酰胺（DMF）中与MWNTs发生反应。基于元素分析、热重分析和滴定，功能化的MWNTs产物（MWNT - NH - PEI）含有6 - 8%（重量）的PEI。该产物在pH值低于9的水中形成稳定乳液，并且可以衍生化形成可分散于有机介质中的烷基化MWNTs。这种MWNT - NH - PEI纳米颗粒还可用于共价或离子逐层组装，以在功能化聚乙烯（PE）薄膜和粉末上形成纳米复合薄膜。通过接触角分析、原子力显微镜（AFM）和共聚焦拉曼显微镜对这种纳米复合薄膜进行了分析。这些分析表明，这些超亲水表面具有微/纳米粗糙度，MWNT纳米颗粒分布大致均匀。如果最终接枝物用氯甲酸乙酯和十八烷酸制备的混合酸酐进行丙烯酸化处理，那么超疏水PE薄膜可以通过MWNT - NH - PEIs与聚丙烯酸的离子逐层自组装或者MWNT - NH - PEIs与甘胆酸的共价逐层自组装来形成。通过五个共价逐层沉积步骤得到的十八烷基化表面的水接触角为165°，滑动角小于5°。通过五个离子逐层沉积步骤得到的相应表面的水接触角为155°，但存在水钉扎现象。离子组装的纳米复合接枝物在酸性条件下不稳定。共价组装的接枝物在化学性质上更稳定。
