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.