Computational modelling and design of nanoporous silica materials

Nanoporous materials, like zeolites or activated carbon, are used in a wide range of applications, from gas separations in the petrochemical industry, to air or water purification, to medical uses like controlled drug delivery. Indeed, the market for nanoporous materials is estimated at ~£1.5 billion, and set to rise to ~£1.8 billion in 2017. Despite their tremendous potential, further developments are limited by our lack of fundamental understanding and control over their synthesis processes, with most discoveries arising from the application of exhaustive searches or heuristic approaches. It is clearly necessary to change this paradigm to enable targeted design of these materials, and computational models are ideally suited for this purpose. Computational design of nanoporous materials would allow us to save time and money by reducing the number of necessary experiments in the path to material discovery, and, more importantly, would enable us to tune the properties of a new material for a specific target application (for example, maximising the affinity of the material towards a given pollutant present in an industrial effluent). The main aim of this research is to develop a multiscale modelling strategy that can describe the entire synthesis process of a nanoporous material, from the precursor solution to the final porous solid. We will use periodic mesoporous silicas (PMS) as a prototype system, because they have been widely studied experimentally, they are made using a templated synthesis process (the structure of the solid is determined by silica/surfactant liquid crystals), and their final structure is particularly amenable to tuning by changing the synthesis conditions.

We will build upon previous groundbreaking research in the PI's group to establish a hierarchy of models of decreasing degree of complexity (and thus increasing computational efficiency), ranging from the quantum-mechanical level, to the classical atomistic level, to the mesoscale level. Lower-level models will be validated against higher-level models and experimental data, maintaining the necessary accuracy while expanding the accessible range of length and time scales. The idea is that using the final model we will be able to generate a complete virtual model of a PMS material based only on knowledge of the initial synthesis conditions - essentially mimicking an actual experiment on the computer. Crucially, this goal relies on developing a model that can cope with chemical reactions of silica in these complex environments, which in itself will constitute a major innovation in the field of computational material science.

This project involves fundamental research at the interface of the traditional disciplines of engineering, chemistry and materials science. As such, the proposed research is very likely to have a significant impact on academic research in these areas: in material science, it will increase our understanding of how nanoporous materials are formed and enhance our ability to discover new nanomaterials; in chemistry, it will shed new light on the interplay of chemical reactions, phase equilibrium and self-assembly processes; in engineering, it will contribute towards a more effective design of nanoporous materials for target applications (e.g., catalysis or gas separations). Methodological developments are also expected, particularly with regards to the proposed multiscale modelling strategy, which is in principle generally applicable to other processes that take place over a wide range of time and length scales.

Because it is focused on tailored material design, this research is likely to lead to profound impact in industries that manufacture nanoporous materials, and silica-based materials in particular. Indeed, the proposed strategy has the potential to change the paradigm of nanoporous material design, replacing the current trial-and-error approaches with computer-aided design solidly anchored on fundamental science. By enhancing our ability to optimise the manufacture of existing materials and the discovery of new ones, this knowledge-based approach will potentially lead to direct economic impact (the world market for nanoporous materials is ~£1.5 billion).

Impact of this research on society will come from novel potential applications of nanoporous materials. For example, porous materials can be designed with ideal properties for controlled drug delivery, increasing the affinity of the solid towards a specific drug, optimising its release rate inside the body, and minimising its eventual adverse effects on human health. Another example is the development of improved water purification membranes based on nanoporous materials, with optimised retention rates for specific pollutants. If we are able to effectively tailor the properties of the material to the specific target application using limited resources, the possibilities are endless. Finally, we will also aim to contribute towards increased public awareness of the benefits of science. Science at the nanoscale is particularly effective at capturing the imagination of young students, which is compounded by the strong visual attractiveness of computer-generated images of molecular simulations.