"Polymers are long molecules comprising repeated chemical units known as monomers. Some polymers, such as polyethylene glycol (PEG), which comprises ethylene glycol (EG) monomers, are very useful as therapeutic agents and as parts of sophisticated nanomedicines, because they regulate the way that a medicine is transported around and retained in the body. Other polymers mimic naturally produced polymers including peptides and oligonucleotides (oligos). However it is extremely difficult to make polymers such as PEG and oligos accurately, because chemical techniques often add a few more or a few less monomers to the chain. For example, in making EG112, a PEG polymer with 112 repeated EG units and a molecular weight close to 5,000 Da, current processes also make EG111, EG113, EG110, EG114, and so on, so that the material is known as polydisperse. This is a problem when it comes to use as part of a medicine, because the different chain lengths can act in different ways in the body, and analysis of multiple species is harder to do accurately. EXACTMER is a start-up company that has licensed a new technology invented at Imperial College London, Nanostar Sieving. A hub molecule with three or more arms is used to form a macromolecular Nanostar. Monomers are added to each of the arms, one by one, to form polymers with an exactly controlled sequence of monomers. After the addition of each monomer, all the debris are removed by molecular sieving through a specially designed membrane. The process is repeated over and over until the desired number of monomers has been added, and then the polymers are cut off the hub and recovered, with all molecules having the same, exact number of monomers. This feasibility project aims to show that this completely new approach can scaled up to produce pure PEGs and oligonucleotides at scales of at least 10 g product per batch, and with rapid cycle times. If we are successful, this will be a breakthrough for PEG fabrication and will enable EXACTMER to launch a range of PEG products of high molecular weight and unprecedented purity. It will enable us to introduce Nanostar Sieving as an alternative to the widely used and expensive solid phase synthesis for peptides and oligonucleotides. We will develop Nanostar Sieving for the assembly of further, more sophisticated nanomedicines, and strive to become the UK based dominant global producer of exact, high value polymers."