Halogen bonding in polymer science: from crystal engineering to functional supramolecular polymers and materials

Halogen bonding (XB) is commonly defined as a non-covalent bond where halogen atoms (X = Cl, Br, I) function as electron acceptors. As an analogue of hydrogen bonding, halogen bonding is attracting steady interest in many fields of research owing to the similarity of its concept. Thus, the combination of a high directionality and intrinsic hydrophobicity associated with a potential fine-tuning of interaction strength makes XB a compelling tool for designing supramolecular functional materials. Over the last decade, an increasing number of papers have been dedicated to the application of halogen bonding in polymer science by designing polymeric self-assembled components, organizing macromolecular entities and templating the formation of polymers. In this regard, the objective of this paper is to highlight the recent developments of this approach by reviewing its applications in topics as diverse as surface functionalization, soft, luminescent and magnetic materials, interpenetrated networks, synthetic methods, and separation and inclusion techniques. The halogen bonds appear particularly tailored for engineering smart devices and further applications in nanotechnologies through bottom-up approaches.