Templated growth of carbon nanotubes with controlled diameters using organic-organometallic block copolymers with tailored block lengths.
Block copolymer thin films fabricated from polystyrene-polyferrocenylsilane (PS-b-PFS) block copolymers on silicon substrates were used as precursors of well-ordered, nanosized growth catalysts for carbon nanotubes (CNTs). The size of the catalytic domains was tuned by changing the molecular weight of the block copolymer, enabling control of the diameter of the CNTs grown from these substrates. CNT growth on catalytic substrates with larger organometallic domain sizes, using acetylene as a carbon source, resulted in enhanced amounts of CNT deposition compared to smaller PFS domains, which exhibited low catalytic activity. The inner and outer diameters of the multi-walled CNTs obtained were typically 8 and 16 nm, respectively, and were not influenced by the catalytic domain sizes. Various annealing strategies in inert or in hydrogen atmosphere were investigated. The use acetylene with an additional hydrogen flow as gas feed resulted in a significant increase in deposition on all PS-b-PFS decorated substrates. Under these conditions, the CNT diameters could be controlled by the catalyst domain sizes, resulting in decreasing diameters with decreasing domain sizes. Multiwalled CNTs with inner and outer diameters of 4 and 7 nm, respectively, and a narrow diameter distribution were obtained.
Roerdink
Monique
M
Department of Materials Science and Technology of Polymers and MESA- Research Institute for Nanotechnology, University of Twente, P 0. Box 217, NL-7500 AE Enschede, The Netherlands.
Pragt
Joris
J
Korczagin
Igor
I
Hempenius
Mark A
MA
Stöckli
Thomas
T
Keles
Yanki
Y
Knapp
Helmut F
HF
Hinderling
Christian
C
Vancso
G Julius
GJ
D002384:Catalysis; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D036103:Nanotechnology; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D009942:Organometallic Compounds / Q000737:chemistry*; D011137:Polystyrenes
D037742:Nanotubes, Carbon; D009942:Organometallic Compounds; D011137:Polystyrenes