Synthesis and physicochemical characterization of aluminium-based hydrogels through the Epoxide Route

SEGOVIA, GUSTAVO; OESTREICHER, VÍCTOR; HUCK-IRIART, CRISTIÁN; ANGELOMÉ, PAULA C.

Encuentro; 31st LNLS Annual Users Meeting (RAU); 2021

Aluminium hydrogels (AlHG) represent a key material owning catalytic properties for a largevariety of industries, specially due to their transparency in a wide range of energies and theirhigh stability. 1,2 However, the chemical nature of the phases, shape and size distribution areimportant aspect that need to be addressed. For instance, precise laboratory-based methods 3would permit the identification of AlHGs growth, the effect over the chemical reactivity, as wellas the physicochemical properties of the material. 1 Furthermore, in recent years, the interest ineco-friendly synthetic procedures has been increased, mainly in obtaining of compounds undermild conditions and aqueous or biocompatible solvents. 4In line with this, the Epoxide Route 5 has shown a high versatility for leading the homogeneousprecipitation at room temperature of several inorganic and hybrid materials, 6,7 including metaloxides/hydroxides, 7 in a highly controllable scenario. 5 In addition, due to this method can beperformed in one step approach and at room temperature (desirable characteristics forsynchrotron experiments) several in situ experiments can be carried out be assessed from kineticto thermodynamic information. 8In this work, the synthesis of AlHGs through the Epoxide Route was characterized via time-resolved Small Angle X-Ray Scattering (SAXS) experiments, performed using synchrotronlight sources, which has allowed the thorough characterization of key features related to thenucleation and growth processes. Interestingly, the results indicate that the AlHG nanoparticleshave a relatively slow growth kinetic, from an initial quasi-spherical morphology which evolvesto a lamellar symmetry (1D to 2D growth process). It is worth mentioning that this growthprocess and the features of the obtained phases are conserved even a with a high concentrationprecursor, a fundamental aspect from the industrial point of view. Additionally, by tuning thenature of the solvent mixture the AlGH nanoparticles size can be enlarged by simply increasingthe ethanol-water ratio. Therefore, this work highlights the use of the Epoxide Route as versatilesynthetic tool for in situ understanding of growth mechanism in the design of new compositeswith unexplored properties. 9