Soft Nanotechnology

Very large molecules / macromolecules / are all around us. They are what plastics are made of, and they also are the major components in glues and paints. A huge industry has grown up to make these synthetic macromolecules, or polymers, for use in plastics. These materials are ubiquitous, and useful, but their applications are not very sophisticated / we see plastics used in packaging, for casings, and for cheap everyday items. But macromolecules are also what make living things work. Biological macromolecules, like proteins and DNA, are not simple structural materials like plastic. Instead, they are the building blocks for the sophisticated but tiny machines that perform life's functions. They store and read genetic information, in plants they use the sun's energy to fuel chemical processes, they form the motors that make our muscles work. Why can't we use our artificial macromolecules in these more sophisticated ways, ways that exploit the properties of individual molecules to make highly efficient machines?The first thing we need is to be able to make molecules that are more complicated than the ones that make up simple plastics like polythene. Synthetic polymer chemistry now permits us to start to do this; we are seeing macromolecules being made that can conduct electricity or interact with light, we can make macromolecules with complicated structures, with different chemical sections joined together according to a predetermined plan. Remarkably, this molecular plan can determine how many molecules arrange themselves; the molecules themselves carry a blueprint which dictates the structures that they form, through a process known as self-assembly . What we now need to do is to understand how to use these sophisticated molecules to do things. Our first efforts will be very crude; we can make a macromolecule attached to a surface change shape, which would allow us to attach or release another molecule. We can design molecule-based systems that can generate forces and propel themselves. We can use our knowledge of the way polymer molecules arrange themselves, particularly when they are in the form of very thin films, to learn how to make more efficient polymer-based solar cells. As we learn more about the details of the way the molecular machines of biology work, and our own ability to synthesise and manipulate synthetic macromolecules grows, we can hope to make molecular machines of greater and greater sophistication.