Accelerated sol–gel synthesis of nanoporous silica via integrated small angle X-ray scattering with an open-source automation platform

Abstract

Sol–gel syntheses can produce diverse arrays of nanomaterials, including mesoporous colloidal silica, within chemical design spaces that can become exceedingly large, complex, and expensive to explore via traditional methods. A new workflow for sol–gel automated synthesis of SiO₂, based on the open-hardware platform Science-Jubilee with integrated small angle X-ray scattering (SAXS), is demonstrated to outline correlations between precursor concentrations and morphological properties including particle size, polydispersity, extent of internal porosity and type of pore-phase order. Development of open and accessible high-throughput experimentation approaches is critical to accelerating the application of bespoke mesoporous silica nanostructures for potential use in chemical separations, catalysis, and drug delivery among other fields. The new hardware and workflow adapts and extends the Science-Jubilee automation platform for sol–gel synthesis and also integrates the NIST-design for the autonomous formulation laboratory (NIST-AFL) to achieve in situ structural characterization using either synchrotron and/or laboratory small-angle X-ray scattering (SAXS) instruments. An experimental campaign for SiO₂ room-temperature sol–gel synthesis using cetyltrimethylammonium bromide (CTAB) and Pluronic F127 surfactants, ammonia and tetraethyl orthosilicate (TEOS), demonstrates that it can reproducibly yield colloidal silica of variable size, dispersity, and internal pore phase order. The results also correlate well with published synthetic outcomes using traditional manual methods.