Multifunctionality of Iodinated Halogen-Bonded Polymer: Biodegradability, Radiopacity, Elasticity, Ductility, and Self-Healing Ability

Abstract

A polymer with high contents of ester bonds and iodine atoms was synthesized, exhibiting sufficient biodegradability and radioactivity for biomedical applications. The iodine moieties of the synthesized polyester can generate halogen bonding between molecules, which may develop additional functional properties through the bonding. In this study, poly­(glycerol adipate) (PGA) was selected and synthesized as a polyester, which was then adequately conjugated with three different types of iodine compounds via the hydroxy groups of PGA. It was found that the iodine compounds could effectively work as donors of halogen bonding. The thermal analysis by differential scanning calorimetry (DSC) revealed that the glass transition temperature increased with the increase in the strength of interactions caused by π–π stacking and halogen bonding, eventually reaching 49.6 °C for PGA with triiodobenzoic groups. An elastomeric PGA with monoiodobenzoic groups was also obtained, exhibiting a high self-healing ability at room temperature because of the reconstruction of halogen bonding. Such multifaceted performance of the synthesized polyester with controllable thermal/mechanical properties was realized by halogen bonding, leading to a promising biomaterial with multifunctionality.

Utilizing Secondary Bonds Formed by Halogen Substituents: Achieving the Dynamic Transition of Low-Bandgap Semiconductor Polymers from Macromolecules to Small Molecules

“…The strength of hydrogen bonds usually depends on the electronegativity of the hydrogen bond acceptor, while the strength of halogen bonds is influenced by the size and polarization ability of the σ hole. Secondary bonds, as reversible noncovalent interactions, play a key role in imparting a self-healing functionality to supramolecular materials, thanks to their dynamic, responsive, and adjustable strength. − During the reformation process after supramolecular framework disassembly, dynamic bond exchange phenomena often occur, highlighting another advantage of secondary bonds in supramolecular materials. − Utilizing this advantage to develop convertible dielectric and semiconductor soft materials is highly appealing.…”