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Covalent Bond Modification


Alfa Chemistry provides customers with covalent bond modification services on the graphene surface. Covalent functionalization of graphene involves combining graphene with newly introduced groups in the form of covalent bonds to improve and enhance its performance.The large number of oxygen-containing groups on the surface of graphene oxide makes the functionalization of covalent bonds easier than on graphene. Covalent bond modification can improve the processability of graphene and bring new functions.

Our covalent bond modification services include, but are not limited to, the following:

  • Modification With Small Organic Molecules

The sp2 carbon structure of graphene can directly react with free radical reagents such as diazonium salts. By selecting an appropriate reaction matrix, the required functional groups can be modified on the surface of various types of graphene. During the preparation of graphene oxide, a large number of functional groups such as hydroxyl, carboxyl, epoxy groups can be added to the surface and edges, which results in graphene oxide having higher chemical activity and lower cost than graphene. Therefore, using graphene oxide as a raw material to carry out organic chemical reactions through the oxygen-containing groups has gradually become the mainstream method of introducing target functional groups.

The common reactions are listed below.

  • Isocyanation
  • Carboxyl Acylation
  • Epoxy Ring Opening
  • Diazotization
  • Addition Reactions
  • Click Chemistry Reactions
  • Friedel-Crafts Reactions
  • Diels-Alder Response

Customized-Graphene-Dispersion-PictureFig 1. Covalent Bonding in Nanohybrid-ER. (Fu J.H, et al. 2019)

  • Covalent Grafting of Polymers

The methods for grafting organic polymers onto the surface of graphene or graphene oxide are generally divided into: "grafting from" and "grafting to". "Graft-from" mainly relies on the use of either “neat” graphene, or graphene in its oxidized form, graphite oxide (GO), upon which initiator sites are fixed from where the polymerization takes place. "Graft-to" refers to the synthesis of macromolecules, and then the functionalized groups on the macromolecules react with graphene or graphene oxide groups to form polymer modified graphene.

Customized-Graphene-Dispersion-PictureFig 2. Two methods for covalent bonding of polymer and graphene.

Properties and Applications

Modified Group Modification Agent Interaction Type Property Application
-C=C-4-Propargyloxydia-zobenzenetetra-fuoroborateDiazotizationWater solubleBiosensors
-OH2-Bromoisobutyryl bromide, NaN3, HC≡C-PSEsterificationGood solubilityPolymer composites
-COOHSOCl2EsterificationConductiveConducted membrane
-OHN2H4, DNAAddition esterificationGood solubilityBiosensors

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  1. Fu J.H, et al. (2019). "Covalent Functionalization of Graphene Oxide with a Presynthesized Metal−Organic Framework Enables a Highly Stable Electrochemical Sensing." ACS Applied Materials & Interfaces. 11, 33238-33244.
  2. Salavagione H.J, et al. (2011). "Recent Advances in the Covalent Modification of Graphene With Polymers." Macromolecular Rapid Communications. 32, 1771-1789
Our products are for research use only and cannot be used for any clinical purposes.

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