Materials

Electronic Materials

The design and synthesis of new small molecules and polymers is essential to the development of functional materials for a variety of electronic applications. The Hawker group has developed small and macromolecules for use in a wide range of applications including lighting, displays, solar cells and batteries. For example, we synthesized and characterized a new class of isomeric building blocks for low bandgap conjugated polymers based on a distorted C=C double bond. A major advantage of these cis- and trans-(bis)thiophene derivatives is the ease of their synthesis and modular structure. While non-planar, the twisted nature of these repeat units still allows for conjugation along the polymer backbones with broad visible and near-infrared absorbance and high solubility. These results demonstrate that the design of new monomers that deviate from the accepted view of conjugated polymer building blocks offer the opportunity to prepare new structures with improved properties and performance for the broad field of polymer-based solar cells and organic electronics.

Gels

Hydrogels have attracted a great deal of attention in the pharmaceutical and biomedical fields based on their desirable properties, such as permeability and biocompatibility, for a variety of applications. For example, hydrogels can be used for drug delivery, wound dressings and tissue engineering. However, conventional hydrogels lack the mechanical strength required for practical use, which is why the Hawker group has devoted effort into improving their properties; this has been achieved through the development of double network, slide-ring, and ionic coacervate hydrogels. As an example, high-performance interpenetrating polymer network (IPN) gels were successfully fabricated via a one-pot, orthogonal, double click strategy. This modular synthesis allows the weight fraction of the tight and loose networks as well as the crosslinking density to be tuned according to the application desired.

Biomaterials

Part of our group focuses on the development of novel materials used for a variety of biomedical applications including the diagnosis and treatment of disease. For example, we developed a modular synthesis for preparing polymeric nanoparticles capable of imaging atherosclerosis by PET imaging techniques. Key to this strategy is the ability to attach different peptides to the nanoparticles, which enables us to target, and therefore image, a variety of diseases. We are also interested in better understanding natural systems by synthetically manipulating or mimicking them. An example of the former is our recent report on an alternative grafting-from strategy for directly engineering the surfaces of live yeast and mammalian cells through cell surface-initiated controlled radical polymerization. This was achieved by developing a cytocompatible PET-RAFT method which gave access to uniform polymers at room temperature within 5 minutes. Our strategy enables chain growth to be initiated directly from chain transfer agents anchored on the surface of live cells using either covalent attachment or non-covalent insertion, while maintaining high cell viability. The capability to graft synthetic polymers from the surfaces of live cells offers the potential to manipulate and control their phenotype and underlying cellular processes. For mimicking nature, the group is interested in the bioinspired control of polymer self-assembly via ligand-metal ion interactions and the synthesis of smart materials that can deliver into specific target cells.