Self-Immolative Poly(Benzyl Ether)s: Design Principles and Controlled Depolymerization.

Self-immolative polymers (SIPs) constitute a sophisticated class of stimuli-responsive materials capable of undergoing complete end-to-end depolymerization upon a single triggering event. Among the various SIP architectures, quinone-methide (QM)-based poly(benzyl ether)s (PBEs) stand out owing to their high structural stability and well-defined disassembly kinetics. This article reviews the fundamental design principles of PBEs, emphasizing the thermodynamic role of their low ceiling temperature (Tc) and their 1,6-elimination mechanism for depolymerization. It also demonstrates how the restoration of aromaticity and the entropic gain drive polymerization ("zipping") of QM monomers and depolymerization ("unzipping") of the polymer backbone into stable monomeric units, respectively. Furthermore, it discusses recent advances in modular end-cap engineering, which enable precise spatiotemporal control over depolymerization in response to chemical, photochemical, and biological stimuli. Overall, by highlighting the applications of PBEs in signal amplification, controlled cargo release, and the development of chemically recyclable materials, this article offers a comprehensive overview of their potential to redefine the boundaries of functional macromolecular design within a sustainable framework.