Thermal management and heat dissipation is a rapidly growing research area. Electronics are ubiquitous in our everyday life. Faster and smaller electronic devices require the miniaturisation of several electronic components distributed on chips with ever-growing density (as of today more than 7 x 109 transistors in about 500 mm2). The heat generated by electronic devices increases exponentially with the density of electronic devices on the same chip. Anisotropic thermally conductive materials able to dissipate heat in one or two in-plane spatial directions while barring conductivity in the out-of-plane direction are ideal materials to dissipate heat effectively without affecting surrounding devices.
Two main techniques exist for the dissipation of the heat generated by an electronic chip: 1) radiators with highly exposed surfaces to maximize efficient heat dissipation from the top surface of the chip, and 2) highly thermally conductive adhesive pastes to dissipate the heat generated at the bottom of the chip. The latter relies on efficient materials that can rapidly and efficiently dissipate this heat.

If graphene and hybrid two-dimensional materials could be incorporated into pastes and composites with a high concentration, this could lead to highly electrically and thermally conductive pastes and composites. Moreover a combination of graphene fibre polymer composites with other two-dimensional materials (such as hexagonal boron nitride which is thermally conducting and electrically insulating) produced in large quantities by solution processing will allow the tuning of electrical properties while retaining high thermal conductivity. This can lead to a new family of electrically insulating and thermally conducting pastes and polymer composites as well as highly anisotropic polymer composites and pastes.

Anisotropic devices with graphene or 2D materials are hard to mass manufacture. Moreover, tailoring of the electrical and thermal properties often requires chemical/physical functionalisation or directional alignment of the 2D flakes which is achieved by a supramolecular approach. These processes are generally difficult to scale-up.

A potential solution is to engineer more accessible amounts of these 2-D materials into the structures of polymers to create nanostructured composites. Anisotropic materials in particular can be deposited or printed using large area deposition techniques. Hence, the ability to combine the tunable properties and processability of polymers with the exceptional properties of 2-D materials may allow the large-scale realisation of a new class of materials.

With this in mind, the aim of this project is to devise and produce a new family of polymer composites, pastes and inks with anisotropic properties (e.g. the management of thermal/electrical conductivity/insulation) that can be produced using modern and industrially-relevant deposition techniques, such as extrusion, injection moulding and 3-D printing. There is also the opportunity to investigate the introduction of 2-D materials into natural polymers, such as cellulose, for electronic textiles to enable cost-effective, easily-recyclable and biocompatible composites that may be introduced into clothing, for instance.

From the perspective of the Department of Engineering's strategic themes, this project aims to advance the manufacturing, design and understanding of engineering materials. Specifically, this includes the nanoscale production and microscale fabrication and characterisation of materials and devices, which are clearly aligned with the department's research ambitions. In terms of the EPSRC's designated research areas, this project will contribute to the development of carbon and graphene technology, composite materials and polymer materials, given its focus on developing the integration of 2D materials into polymer composites.