Isolation of Pristine Electronics Grade Semiconducting Carbon Nanotubes by Switching the Rigidity of the Wrapping Polymer Backbone on Demand

详细信息    查看全文

• 作者：Yongho Joo ; Gerald J. Brady ; Matthew J. Shea ; M. Bel茅n Oviedo ; Catherine Kanimozhi ; Samantha K. Schmitt ; Bryan M. Wong ; Michael S. Arnold ; Padma Gopalan
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：October 27, 2015
• 年：2015
• 卷：9
• 期：10
• 页码：10203-10213
• 全文大小：807K
• ISSN：1936-086X

文摘

Conjugated polymers are among the most selective carbon nanotube sorting agents discovered and enable the isolation of ultrahigh purity semiconducting singled-walled carbon nanotubes (s-SWCNTs) from heterogeneous mixtures that contain problematic metallic nanotubes. The strong selectivity though highly desirable for sorting, also leads to irreversible adsorption of the polymer on the s-SWCNTs, limiting their electronic and optoelectronic properties. We demonstrate how changes in polymer backbone rigidity can trigger its release from the nanotube surface. To do so, we choose a model polymer, namely poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(6,60-(2,20-bipyridine))] (PFO-BPy), which provides ultrahigh selectivity for s-SWCNTs, which are useful specifically for FETs, and has the chemical functionality (BPy) to alter the rigidity using mild chemistry. Upon addition of Re(CO)₅Cl to the solution of PFO-BPy wrapped s-SWCNTs, selective chelation with the BPy unit in the copolymer leads to the unwrapping of PFO-BPy. UV鈥搗is, XPS, and Raman spectroscopy studies show that binding of the metal ligand complex to BPy triggers up to 85% removal of the PFO-BPy from arc-discharge s-SWCNTs (diameter = 1.3鈥?.7 nm) and up to 72% from CoMoCAT s-SWCNTs (diameter = 0.7鈥?.8 nm). Importantly, Raman studies show that the electronic structure of the s-SWCNTs is preserved through this process. The generalizability of this method is demonstrated with two other transition metal salts. Molecular dynamics simulations support our experimental findings that the complexation of BPy with Re(CO)₅Cl in the PFO-BPy backbone induces a dramatic conformational change that leads to a dynamic unwrapping of the polymer off the nanotube yielding pristine s-SWCNTs.