Structural Design Strategy of a Biobased Allyl Compound with Dynamic Boronic Ester Bonds to Form Rigid-Soft Self-Healing Polymer Networks via Thiol-Ene "Click" Photopolymerization for Integrated Preparation of a Flexible Device

Fabricating biobased flexible polymers with high toughness and self-healing ability will promote sustainable development of the fast-growing flexible electronic industry. Herein, a biobased allyl compound (BAMDB) with boronic ester bonds was synthesized from renewable eugenol and then combined with multifunctional thiol via thiol-ene "click" photopolymerization to form a series of flexible networks (BAMDB-SH). Their integrated performance, including thermal, optical, and mechanical properties as well as self-healing behavior, was studied. Their glass transition temperature ranged from 42 to 55 degree celsius and showed high transparency (88.2-89.3% at 550 nm). At the same time, BAMDB-SH3 has the most excellent comprehensive mechanical properties with a tensile strength, an elongation at break, and a toughness of 29.8 MPa, 194.3%, and 35.3 MJ m(-3), respectively, owing to its rigid-soft network structure with appropriate cross-linking density. Depending on the dynamic exchange of boronic ester bonds, BAMDB-SH3 networks could be healed in 30 min at 80 degree celsius with a high self-healing efficiency of 98%. In addition, based on the excellent comprehensive performance and self-healing properties of BAMDB-SH3, it was used to prepare a sandwich sensor by integrated encapsulation of silver nanowires for wrist activity detection, demonstrating the potential applications of BAMDB-SH in flexible devices.