Formation Of Nanowires From Pentacene Derivatives By Single-particle Triggered Linear Polymerization

¹Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Osaka, Japan

²Japan Atomic Energy Agency Takasaki, Gunma, Japan

³Center for Collaborative Research, Anan National College of Technology, Tokushima, Japan

Adv. Mater. Lett., 2015, 6 (2), pp 99-103

DOI: 10.5185/amlett.2015.5720

Publication Date (Web): Feb 08, 2015

Copyright © IAAM-VBRI Press

E-mail: t-sakurai@chem.eng.osaka-u.ac.jp, seki@chem.eng.osaka-u.ac.jp

Abstract

The present paper highlights the development of organic nanowires from small-molecular organic compounds through intra-track chemical reactions by using ion beams.  Thin films of pentacene derivatives, 6,13-bis(triethylsilylethynyl)pentacene (TES-Pn) and 6,13-bis((triisopropylsilyl)ethynyl)pentacene (TIPS-Pn), were subjected to high-energy particle irradiation at a fluence of 10⁸–10¹⁰ cm^–2 and thereafter developed by organic solvents. This method, referred as Single-particle Triggered Linear Polymerization (STLiP), afforded the isolation of wire-shaped nanomaterials on a substrate that were visualized by atomic force microscopy and scanning electron microscopy.  These derivatives exhibited high enough propagation and cross-linking reaction efficiencies (G) as G_TES-Pn of > 7 and G_TIPS-Pn of  > 5 (100 eV)^–1, whose values are significantly larger than those observed for previously studied simple cross-linking reactions observed in other polymeric materials, being apparently in the G-value range of chain reactions.  On the other hand, the pristine pentacene and derivative without (trialkylsilyl)ethynyl moiety did not give any nanowires. Considering these observations, highly efficient intra-track propagation/polymerization/cross-linking reactions would take place due to the introduction of (trialkylsilyl)ethynyl groups, resulting in the formation of one-dimensional nanostructures based on small molecules. The STLiP technique serves as a versatile and easy nanofabrication tool for small molecular materials and the resultant nanowires with high functional density are potentially usable as optical, electronic, and sensor materials.

Keywords

Nanowire, pentacene, ion beam, ion track, organic materials.