Application of Chemical Force Microscopy for Finding Selective Functional Groups for Discriminating Different Electronic Type Single-Walled Carbon Nanotubes

Abstract

We recently reported a noncovalent chemistry bead-based method that can sort single-walled carbon nanotubes (SWNTs) to ultrahigh purity. The method is based on the higher affinity of functionalized agarose beads for M­(etallic) carbon nanotubes in acidic pH versus S­(emiconducting) SWNTs based on the selective charge reversal of metallic carbon nanotubes. However, fundamental understanding of the relative selective affinity of various functional groups for certain electronic type nanotubes remains somewhat lacking. We show that the chemical force microscopy (CFM) technique can measure the subtle differences between various common functional groups (such as −NH2, −OH, −SO3H/–SO3 –Na+, −NO2, etc.) and the different electronic types of SWNTs. We show that the amine-functionalized alkane has significantly higher interaction forces with S SWNTs. On the other hand, SO3 –Na+- and NO2-functionalized naphthalene show significantly higher interaction forces with M SWNTs compared with S SWNTs; the −SO3H substitution on an alkane, however, shows no significant selectivity for any single electronic type of SWNTs. We discovered two novel molecules (sodium 4-amino-1-naphthalenesulfonate and 1-amino-4-nitronaphthalene) that are able to have significantly higher interaction force with M SWNTs and provide complete electronic type discrimination over the entire nanotube diameter range. We also show that the CFM platform can be applied to distinguish between M or S tubes from an as-grown SWNTs mixture in air. The platform can also be applied for studying the effect of solvent (water) on the selectivity. It is anticipated that our new CFM method using functionalized tips will be able to accelerate the development of noncovalent separation strategies for improved nanotube electronic type separation.

Interaction between carbon nanotubes with functional groups and epoxy resin and its effect on thermal properties of carbon nanotubes/epoxy composites

“…Friddle et al 33 performed a direct measurement on adhesive force to understand the interactions between CNTs and chemical functional groups using atomic force microscope probes functionalized with specific functional groups. Wang et al 34 investigated the non-covalent interaction force between several types of different functionalized compounds and single-walled CNTs. It indicated that the amino-terminated alkane has a higher interaction force with the single-walled CNTs.…”

“…7,13,18,24,28,32,[35][36][37][38][39][40][41][42] However, a direct experimental evidence of the interaction between CNTs and polymer before and after the composite preparation is still lacking. 17,33,34,[43][44][45] In this article, amino functionalized CNTs (NH 2 -CNTs) and hydroxyl functionalized CNTs (OH-CNTs), which are supposed to form different interfaces between CNTs and epoxy resin in composites, were investigated, and pristine CNTs (p-CNTs) were used for reference. We try to reveal the physical and chemical forces between CNTs and epoxy molecules through several methods, such as surface energy analysis (SEA), atomic force microscopy (AFM), and differential scanning calorimetry (DSC).…”

Fabrication of Carbon Nanotube Thin Films for Flexible Transistors by Using a Cross‐Linked Amine Polymer

“…[5] Because these amine reagents functionalize hydroxyl groups on the highly oxidized surface, this fabrication method cannot be applied to flexible polymerics ubstrates. Most reports on flexible TFTsu sing s-SWCNTsr elied on specialized techniques such as aerosold epositions [7] or transfer processes. [8] Therefore, it is essential to develop an NH 2 -terminated surface on polymerics ubstrates to fabricate SWCNT thinf ilms.…”