Metastable Polymers for Circular 3D Printing

Abstract

ABSTRACT Reducing waste and enabling material reuse are central goals for sustainable advanced manufacturing. In light‐based 3D printing, this requires moving beyond permanent networks toward systems that can be easily returned to their original molecular building blocks, while preserving good performance. Here, a shift toward metastable, 3D printable polymers is introduced, which are intrinsically programmed for controlled depolymerization under mild conditions, enabling circular recovery. This concept is realized using self‐immolative polymers (SIPs), which undergo triggered, domino‐like depolymerization upon activation of a specific labile unit. These polymers are formulated for high‐resolution digital light processing 3D printing, yielding mechanically robust structures. Upon exposure to a defined trigger, the printed networks rapidly (in seconds) and completely disassemble under ambient conditions, regenerating their pristine monomers. These are recovered in near‐quantitative yield and subsequently reprocessed into chemically identical printable polymers. This metastability‐driven approach establishes a transformative pathway for circular 3D printing.