Designing New Phases of Molecular Porous Organic Materials: Liquids, Liquid Crystals, and Glasses

Porous materials are important in a wide variety of applications, such as the capture of greenhouse gases and the separation of chemical mixtures that account for a large percentage of the world's energy consumption. These materials are normally crystalline ordered solids and have an extended framework structure, but this is not a pre-requisite for utility in these applications. For example, the use of molecular porous organic materials such as porous organic cages, and the recent realisation of new classes and phases such as porous liquids and melt-quenched porous glasses, offer alternative approaches and potentially unique applications which are not possible for crystalline ordered solids.

Porous organic cages are discrete molecular species assembled in a modular fashion from at least two building blocks, and they contain a permanent cavity that is accessible to gases through windows - this makes them solution processable, unlike porous solids with an extended framework structure. These cages are extremely versatile and can be directed to pack together in the solid state, a bit like Lego building blocks, to form crystalline solids with interconnected pore networks, or they can be modified to access different classes and phases including porous liquids and unordered glasses. Porous liquids, or liquids with holes, are a recently reported new class of porous material which combines the mobility of a liquid with the properties of a porous solid, and as such have the ability to be pumped around a continuous system, facilitating guest loading and unloading steps. It is also possible to melt-quench liquid organic cages to form porous glasses, offering an alternative method for directly casting membranes for molecular separations which typically require the use of solvent or an additional polymeric additive.

The vision of this project is to explore and develop novel phases and classes of molecular porous organic materials, substantially extending the range of those available. Specifically, the aim is to unlock new types of porous liquids and glasses, and to design in functionality that gives access to new phases and classes of porous materials such as porous liquid crystals - a phase that exists between an ordered porous solid and a disordered porous liquid. This will allow us to gain a fundamental knowledge and understanding of each type, thus enabling us to begin to develop an understanding of the structure-property relationships. Ultimately, the realisation of new phases and classes of porous materials has the potential to offer major advances in the area of porous materials for more selective gas capture and energy efficient separations.