Liquid Metal‐Based Bifunctional Catalysis: Bridging Lactone Polymerization, Polyester Recycling, and Sustainable Flexible Electronics

ABSTRACT

Catalysts enabling both lactone polymerization and polyester depolymerization are essential for achieving chemical recyclability, yet the development of low‐cost, efficient, and multifunctional catalysts remains a major challenge. Herein, liquid metals (LMs), especially gallium (Ga), which served as dual‐functional catalysts, facilitated both the ring opening polymerization (ROP) of lactones and their subsequent depolymerization back to monomers. Using 0.2 vol% Ga as the catalyst, homopolymerization and copolymerization of p‐dioxanone (PDO) and ε‐decalactone (ε‐DL) were efficiently realized. The polymerization mechanism was studied. Subsequently, the depolymerization of PPDO and PPDO‐ co ‐PDL under Ga was investigated. Ga catalysis enabled a remarkable depolymerization efficiency of up to 98%, along with a 25% reduction in activation energy. Finally, PPDO‐ co ‐PDL polyols via Ga catalysis were used to synthesize PPDO‐ co ‐PDL thermoplastic polyurethanes (TPUs). The soft segment of TPUs could be chemically recycled using a Ga catalyst, whereby PDO and ε‐DL monomers were recovered. Beyond catalytic performance, LMs could also render the TPUs applicable to sustainable flexible electronics. PPDO‐ co ‐PDL TPUs with 15 vol% Ga could serve as electronic inks for 3D printing, with the corresponding films suitable for electromagnetic shielding. By integrating catalytic functions toward polymerization and depolymerization with flexible nanofiller roles, LMs provide a new strategy for recyclable flexible electronics.