Nanocatalysts with Tunable Properties Derived from Polystyrene-b-poly(vinyl pyridine) Block Copolymer Templates for Achieving Controllable Carbon Nanotube Synthesis

Abstract

Chemical vapor deposition, one of major carbon nanotube synthesis techniques, has demonstrated great promise for substrate-based carbon nanotube device applications. To understand carbon nanotube growth mechanisms for achieving controllable synthesis, thereby producing carbon nanotubes with consistent and predefined behavior for materializing their highly touted properties, it is imperative to develop a methodology to create nanocatalyst systems controllably with great tunability. In this paper, a comparative study of polystyrene-b-poly(4-vinyl pyridine) versus polystyrene-b-poly(2-vinyl pyridine) as templates for creating nanocatalysts is presented. Creating uniform and periodically ordered nanocatalyst arrays with tunable size and spacing is demonstrated. A scaling relationship between nanocatalyst spacing and polystyrene block length for polystyrene-b-poly(2-vinyl pyridine) is elicited. The potential of synthesizing nanocatalysts with adjustable composition is discussed. The ability to tailor nanocatalyst size and spacing by varying block lengths has been demonstrated to promote controllable synthesis of carbon nanotubes with adjustable diameter and density. Finally, an example of using such highly controlled nanocatalysts derived from the block copolymer template approach, to study the effect of substrate on carbon nanotubes synthesis, is described.

Characterization of single‐walled carbon nanotubes synthesized using iron and cobalt nanoparticles derived from self‐assembled diblock copolymer micelles

“…Self‐assembled block copolymers have been widely employed to create periodically ordered nanoparticle arrays on various substrates. Iron, cobalt, nickel and gold nanoparticles prepared with the block copolymers have been successfully used for the synthesis of SWCNTs 7–10, 13, 16, 17. It has been demonstrated that metal nanoparticle arrays with adjustable spacing, size and composition can be prepared using a solution micelle template formed by polystyrene‐ b ‐poly(vinylpyridine).…”

“…It has been demonstrated that metal nanoparticle arrays with adjustable spacing, size and composition can be prepared using a solution micelle template formed by polystyrene‐ b ‐poly(vinylpyridine). These nanoparticles are excellent catalysts enabling the growth of high‐quality and low‐defect SWCNTs 8–10, 16, 17…”

“…Cobalt nanoparticles resulted in long and small diameter SWCNTs, which are particularly important for many applications. Since nanoparticles synthesized by this method do not agglomerate, CNT growth yield can be calculated 9a. The growth yield is defined by the number of tubes vs. the number of nanoparticles.…”

“…This is manifested by many experimental results suggesting that there is a close correlation between the CNT diameter and the size of catalyst nanoparticle 5–7. Many single metallic and bimetallic nanoparticles, such as iron,5–9, 10b cobalt,9, 10b gold,10a copper11 and nickel,9a, 10b have been used as Nanocatalysts to decompose carbon vapor precursors. Among them, iron and cobalt nanoparticles have been regarded as two of the most effective catalyst systems due to their ability to produce relatively high yield CNTs with wide process window.…”

Directed self-assembly of PS-b-PMMA block copolymer using HSQ lines for translational alignment

“…With PS-b-P4VP, NP inclusion can be done either by depositing the NPs aer the self-assembly process or inclusion of the desired ratio of NP to the diblock copolymer solution before spin coating. For example, wellordered micelle and cylindrical microdomains have been reported in PS-b-P4VP BCPs for metal inclusion to fabricate arrays of iron nanocatalyts, 26 copper nanocatalyts, 27 titania NPs, 28 and iron platinum NPs.…”