Facile asymmetric modification of graphene nanosheets using Κ-carrageenan as a green template

The synthesis of Janus nanosheets using kappa-carrageenan (kappa-Ca) as a green template endows a greener and more straightforward method compared to traditional approaches of using wax template. We hypothesize that the hydrogen bonding interaction between kappa-Ca and graphene oxide (GO) allows partial masking of GO's single facet, paving the way for the asymmetric modification of the exposed surface. GO is first encapsulated within the porous hydrogel matrix formed by kappa-Ca to isolate one of the facets. The exposed surface was then selectively hydrophobized to produce an amphiphilic asymmetrically modified graphene oxide (AMGO). The properties of AMGO synthesized under different kappa-Ca/GO ratios were studied. The kappa-Ca/GO interactions and the properties of GO and AMGO were investigated and characterized. AMGO was successfully produced with a yield of 90.37 % under optimized synthesis conditions. The separation of kappa-Ca and AMGO was conducted without organic solvents, and the kappa-Ca could be subsequently recovered. Furthermore, the porous hydrogel matrix formed by kappa-Ca and GO exhibited excellent shape-retaining properties with high thermal tolerance of up to 50 degrees C. Given these benefits, this newly developed method endows sustainability and open the possibility of formulating more flexible material synthesis protocols. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

The synthesis of Janus nanosheets using kappa-carrageenan as a green template provides a greener and more straightforward method compared to traditional approaches. By effectively masking one facet of graphene oxide through hydrogen bonding interactions, an asymmetrically modified graphene oxide is produced. This newly developed method offers sustainability and flexibility in material synthesis protocols.