Click Chemistry on Solution-Dispersed Graphene and Monolayer CVD Graphene

Abstract

Graphene from two different preparative routes was successfully functionalized with 4-propargyloxybenzenediazonium tetrafluoroborate in order to study a subsequent attachment by click chemistry (1,3-dipolar azideÀalkyne cycloaddition) of a short chain polyethylene glycol with terminal carboxylic end group (PEG-COOH). The reaction steps were studied by FTIR and Raman spectroscopies, as well as zeta-potential and surface tension measurements. In the first route, pristine graphene was surfactant dispersed from a stage controlled expanded graphite before reaction, resulting in colloidally stable dispersions after dialysis removal of the surfactant following the two functionalization steps. The chemistry was shown to increase the zeta-potential from À45.3 to À54.6 mV and increase the surface tension from 48.5 to 63.0 mN/m compared to those of the precursor solution. The magnitudes of the zeta-potential and the resulting solution concentration were shown to increase with grafting density up to 14.2 μg/mL. A colloidal stability model was used to estimate the maximum grafting density of the PEG-COOH groups yielding a value of 1 per 10 nm 2 . Raman mapping before and after the two-step functionalization suggests that edges and defects are preferentially reacted. In the second route, we investigated the same click chemistry functionalization on chemical vapor deposition (CVD) synthesized monolayer graphene films, which showed higher reactivity than solution-dispersed graphene. Because these methods do not originate with the more oxidized forms of graphene, the results point to new ways of more precisely controlling the chemistry of graphene.

Modulation of the exfoliated graphene work function through cycloaddition of nitrile imines

“…S4 (ESI ‡) shows a structure with several height levels (terraces) and this suggests the collapse of two exfoliated flakes, i.e., the dispersed graphene tends to aggregate readily during the deposition process. 80 The small heights of the pyrazoline rings mean that a similar situation was evident from the AFM image of 3b (Fig. 4).…”

Understanding and controlling the substrate effect on graphene electron-transfer chemistry via reactivity imprint lithography

“…3 The chemical functionalization of graphene is important for enabling these applications, and has been explored via covalent 4,5 and noncovalent [6][7][8] schemes. The functionalization of graphene with aryl diazonium salts 4,[9][10][11][12][13][14][15][16] results in the opening of a band gap 10,13,[17][18][19] and shifting of the Fermi level, 10 which are both desirable for the fabrication of electronic devices. In addition, the functional groups on the diazonium moiety can be tailored by organic chemistry so that various chemical characteristics to be coupled to graphene.…”

“…In addition, the functional groups on the diazonium moiety can be tailored by organic chemistry so that various chemical characteristics to be coupled to graphene. 9 Graphene is strongly influenced by the underlying substrate. While SiO 2 /Si substrates are compatible with device fabrication, their roughness and charged impurities lead to electron-hole charge fluctuations or puddles that scatter carriers and inhibit electronic device performance.…”

The Functionalization of Graphene and Graphene Oxide via Click Chemistry

“…图 10 通过点击化学修饰石墨烯的合成路线 Figure 10 The synthesis route for the chemical modification of GS via "click" chemistry Salavagione 等 Figure 11 The synthesis route for azido-functionalization of DPP and click reaction for DPP-G Strano 等 [124] 将聚乙二醇羧酸点击在石墨烯的表面, Figure 12 The synthesis route for diazonium reaction and click chemistry functionalization on graphene sheets Figure 13 The synthesis of the RAFT CTA-modified RGO, and in situ RAFT polymerization of NIPAM on the surfaces of RGO sheets 2012 年, Salavagione 等 [103] 通过点击化学将聚芴类 高分子化合物连接在石墨烯的表面, 并研究了石墨烯对 聚芴的荧光猝灭效应. 在他们的报道中, 通过重氮化合 物完成了对石墨烯的炔基化修饰, 这种修饰改性的方法 比重氮盐方法简单方便.…”

“…G 频带在 1580 cm -1 左 右 [103,104,105,122,124,126,127] G D 频带在 1330 cm -1 左右 [95,104,105,126] 或 1350 cm -1 左右 [96,103,122,127] G 频带在 1600 cm -1 左 右 [99,103,104,105,107] Raman GO D 频带在 1330 cm -1 左右 [104,105,107] G 带为石墨(Graphite)…”