The future of sequence-defined polymers

The objective of this perspective article is to critically analyze the emerging domain of sequence-defined polymers and to discuss future challenges and trends in the field. Sequence-defined polymers are macromolecules, in which the monomer arrangement is perfectly controlled from one chain-end to the other. They therefore have a defined chain-length and primary structure. This article focuses mainly on synthetic polymers and does not provide an in-depth discussion about the chemical synthesis of biopolymers (i.e. nucleic acids and proteins) and biopolymer mimics (i.e. peptidomimetics and xeno-nucleic acids). Although the synthesis of non-biological sequence-defined polymers was initially a challenge, it has grown over the last fifteen into a mature discipline. Indeed, major progress has been made for the synthesis, characterization and application of these manmade macromolecules. Thus, in the first section of this article, a brief summary of the most important achievements is provided. For instance, synthesis by multistep-growth "polymerization", sequencing (i.e. complete sequence determination) and emerging applications (e.g. data storage, anti-counterfeiting technologies, catalysis, selective drug carriers) are discussed. The second section of this article provides an in-depth discussion about the future of the field. Despite enormous progress, there are still major limitations regarding the synthesis and applicability of sequence-defined polymers. Moreover, some important properties of sequence-defined polymers still have to be discovered. All these aspects are discussed in details herein and some priority topics are suggested for the future.