Paloniemi Hanna, Lukkarinen Marjo, Aäritalo Timo, Areva Sami, Leiro Jarkko, Heinonen Markku, Haapakka Keijo, Lukkari Jukka
Department of Chemistry, University of Turku, 20014 Turku, Finland.
Langmuir. 2006 Jan 3;22(1):74-83. doi: 10.1021/la051736i.
We have used anionic and cationic single-wall carbon nanotube polyelectrolytes (SWNT-PEs), prepared by the noncovalent adsorption of ionic naphthalene or pyrene derivatives on nanotube sidewalls, for the layer-by-layer self-assembly to prepare multilayers from carbon nanotubes with polycations, such as poly(diallyldimethylammonium) or poly(allylamine hydrochloride) (PDADMA or PAH, respectively), and polyanions (poly(styrenesulfonate), PSS). This is a general and powerful technique for the fabrication of thin carbon nanotube films of arbitrary composition and architecture and allows also an easy preparation of all-SWNT (SWNT/SWNT) multilayers. The multilayers were characterized with vis-near-IR spectroscopy, X-ray photoelectron spectroscopy (XPS), surface plasmon resonance (SPR) measurements, atomic force microscopy (AFM), and imaging ellipsometry. The charge compensation in multilayers is mainly intrinsic, which shows the electrostatic nature of the self-assembly process. The multilayer growth is linear after the initial layers, and in SWNT/polyelectrolyte films it can be greatly accelerated by increasing the ionic strength in the SWNT solution. However, SWNT/SWNT multilayers are much more inert to the effect of added electrolyte. In SWNT/SWNT multilayers, the adsorption results in the deposition of 1-3 theoretical nanotube monolayers per adsorbed layer, whereas the nominal SWNT layer thickness is 2-3 times higher in SWNT/polyelectrolyte films prepared with added electrolyte. AFM images show that the multilayers contain a random network of nanotube bundles lying on the surface. Flexible polyelectrolytes (e.g., PDADMA, PSS) probably surround the nanotubes and bind them together. On macroscopic scale, the surface roughness of the multilayers depends on the components and increases with the film thickness.
我们使用了通过离子萘或芘衍生物在纳米管侧壁上的非共价吸附制备的阴离子和阳离子单壁碳纳米管聚电解质（SWNT-PEs），通过逐层自组装由碳纳米管与聚阳离子（如聚（二烯丙基二甲基氯化铵）或聚（烯丙胺盐酸盐）（分别为PDADMA或PAH））和聚阴离子（聚（苯乙烯磺酸盐），PSS）制备多层膜。这是一种用于制造任意组成和结构的薄碳纳米管薄膜的通用且强大的技术，并且还允许轻松制备全SWNT（SWNT/SWNT）多层膜。用可见-近红外光谱、X射线光电子能谱（XPS）、表面等离子体共振（SPR）测量、原子力显微镜（AFM）和成像椭偏仪对多层膜进行了表征。多层膜中的电荷补偿主要是内在的，这表明了自组装过程的静电性质。初始层之后多层膜的生长是线性的，并且在SWNT/聚电解质膜中，可以通过增加SWNT溶液中的离子强度来大大加速生长。然而，SWNT/SWNT多层膜对添加电解质的影响更具惰性。在SWNT/SWNT多层膜中，每吸附一层，吸附导致沉积1-3个理论纳米管单层，而在添加电解质制备的SWNT/聚电解质膜中，标称SWNT层厚度高2-3倍。AFM图像表明，多层膜包含位于表面的纳米管束的随机网络。柔性聚电解质（例如，PDADMA，PSS）可能围绕纳米管并将它们结合在一起。在宏观尺度上，多层膜的表面粗糙度取决于组分并且随膜厚度增加。
