Supramolecular Assembly of Gelatin and Inorganic Polyanions: Fine-Tuning the Mechanical Properties of Nanocomposites by Varying Their Composition and Microstructure

Abstract

International audienceA series of bionanocomposites has been synthesized through a complex coacervation process inducing the assembly of gelatin with a wide range of inorganic polyanions (IPyAs) differing by their diameter and charge and including polyoxometalates (POMs) and a polythiomolybdate cluster. The microstructure and stoichiometry of these hybrid coacervates, which are strongly dependent on the charge matching between both components, have been studied by combining Fourier transform infrared (FT-IR) spectroscopy, solid-state nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), elemental analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) elemental mapping. The mechanical properties of these materials were deeply characterized by tensile measurements at large deformation, revealing different behaviors (i.e., elastomer and ductile), depending on the nature of the IPyA. It is noteworthy that the mechanical properties of these bionanocomposites are strongly enhanced, compared to pure gelatin hydrogels. When attempting to connect structure and properties in these bionanocomposites, we have demonstrated that the density of cross-links (gelatin triple helices and IPyA) is the key parameter to control the extensibility of these materials

Single‐Molecule Magnet Behavior of Individual Polyoxometalate Molecules Incorporated within Biopolymer or Metal–Organic Framework Matrices

“…Upon drying, the viscous phase evolves to a glassy compound, owing to the vitreous transition of gelatin. As previously reported for other POM–gelatin bionanocomposites, Fe 6 W 18 POMs are confined within a gelatin network composed of coils and triple helices. Its orange color suggests the presence of the POMs, which was confirmed afterwards by a series of characterizations.…”

“…Fe 6 W 18 @Gel was synthesized following a coacervation process previously described for the immobilization of POMs in gelatin matrix . This process is mainly based on attractive electrostatic interactions between negatively charged POMs and positively charged gelatin chains.…”

“…Gelatin (Figure a), a cheap, abundant macromolecule obtained by hydrolytic degradation of mammalian or fish collagen, is widely used in food and pharmaceutical industries, and can form transparent and elastic gels. Gelatin has already proven a good matrix for the synthesis of bionanocomposites with diamagnetic POMs exhibiting topologies as different as heptamolybdate, decavanadate, Keggin‐type, or Keplerate and crown‐shaped species …”

Understanding and Tuning Bioinorganic Interfaces for the Design of Bionanocomposites

“…The influence of incorporation of polyoxometallates on the mechanical behaviour of gelatin has also been studied with other POMs 28. Overall, these studies confirm that POMs can reinforce gelatin‐based materials by acting as physical cross‐linkers above 27 °C and by stabilizing the thermally induced triple helices below 27 °C.…”

Novel Keplerate type polyoxometalate-surfactant-graphene hybrids as advanced electrode materials for supercapacitors

“…Mo132 is a POM nanocapsule displaying an icosahedral symmetry and comprising over 500 atoms, being arguably one of the largest spherical POM ever produced [60]. Since its first successful synthesis by Müller [57] this building block attracted a great interest because of its structural and catalytic properties [61,62]. Hitherto, only one article reported on the use of Mo132 as composite component in metal oxide semiconductor photoelectrodes [63].…”