Functionalization of Single-Walled Carbon Nanotubes (SWNTs) with Stimuli- Responsive Dispersants

摘要

Carbon nanotubes (CNTs) have promised great opportunities for the development of next-generation materials science and technology, given their extraordinary mechanical and electronic properties. Ever since their first discovery in the early 1990s [1], carbon nanotubes have not only attracted enormous academic curiosity, but also fueled up extensive and continued pursuit of technological applications in numerous fields, such as field effect transistors, light emitting devices, photovoltaic materials, chemical sensors, actuators, and catalysis [2-4]. Carbon nanotubes belong to a unique family of carbon allotrope with a tubular shape, a diameter of 1-2 nm, and a length on the micron scale. Depending on the structure of layers, carbon nanotubes can be singlewalled and multiple-walled. Conceptually, a single-walled carbon nanotube can be perceived as being formed by wrapping a single layer of graphene sheet into a cylindrical structure. According to the different angles in which the graphene sheet is wrapped, the resulting tubes can be characterized as different types, such as “zigzag”, “armchair”, and “chiral”, defined by a chiral vector (Ch) and two indices (n,m) [5]. Typically, if m = 0, the SWNTs are called “zigzag” nanotubes, if n = m, they are “armchair”, and if otherwise, the SWNTs are categorized as “chiral”. Apart from chirality, SWNTs can also be simply divided into two electronic types, namely metallic and semiconducting, based on their electronic properties. Nanotubes with chiral indices n-m = 3x (x is an integer) are usually metallic, while others are semiconducting.