Supramolecular gel based on the cyclodextrin inclusion assembly of Ag-Fe3O4 nanodimers and Pluronic F127

• The supramolecular gel with a flower-like morphology structure has been prepared.
• The Ag-Fe3O4 nanodimer and carboxylated cyclodextrin play a key role to the gel morphology.
• The introduction of nanodimers to gel may bring potential applications from both Ag and Fe3O4.

Being considered as building blocks, the inorganic nanodimer particles such as Ag-Fe3O4, Cd-Se and Pt-Fe3O4, have attracted much attention because of their capability of dual surface functionalization and potential applications in field-emission, data storage and photovoltaic devices. For these motivations and as a continuation of our previous study, a gel with flower-like morphology based on Ag-Fe3O4 nanodimers has been constructed with the carboxylated cyclodextrin (MAH-CD) and Pluronic F127 molecules in mixed solvent of cyclohexane and water. The morphology of Ag-Fe3O4 nanodimers and structure of MAH-CD were characterized by transmission electron microscopy (TEM) and nuclear magnetic resonance (NMR) respectively. The mechanism of gel formation is discussed along with the data obtained from rheological measurement, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transformation infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Each Ag-Fe3O4 particle was coated by lots of MAH-CD molecules, which were threaded by F127 chains. The gel fabrication is controlled by the inclusion of MAH-CD with F127, the interaction between the carboxyl group and the Fe3O4 surface. The cyclohexane molecules in gel were trapped with F127 by cyclodextrin, which may be packed orderly through hydrogen bond. Meanwhile, the Fe3O4 side of nanodimers provides the anchoring position for carboxyl group to induce the formation of gel. Such an Ag-Fe3O4 nanodimer initiated gel can be used either based on Ag side for catalytic and sensing properties, or based on superparamagnetism from Fe3O4 side.

The inclusion between carboxylated cyclodextrin (MAH-CD) and block polymer F127 forms a column-like structure, which may be close-packed to produce a crystal flake. With the help of anchoring cyclodextrin through the carboxyl group on Ag-Fe3O4, a flower-like gel morphology could be built by the directionally arranged flakes. Without carboxyl, however, the inclusions with normal β-CD could only result in a gel with a bulk solid morphology.Figure optionsDownload as PowerPoint slide