Perfectly Alternating Copolymerizations of Methacrylates and Coumarin to Robust C–C Main-Chain Polymers with Full Degradability and Depolymerizability

This contribution reports the first copolymerization of methacrylates with simple, commercially available, and biorenewable coumarin (CM). The key to this achievement lies in the rational design of a new Al(C₆F₅)₃/P^<i>n</i>Bu₃ Lewis pair cooperative catalyst, which possesses several unique features, including high efficiency, living nature, and, more strikingly, perfectly alternating sequence control. Computational studies elucidate that kinetic control, enabled by different attractive London dispersion interactions between enolaluminate active species and two monomer substrates, is a decisive factor for alternating sequence control. Accordingly, a series of alternating vinyl copolymers with a high molecular weight (<i>M</i>_n) of up to 330.8 kg/mol can be synthesized directly from commercial/general vinyl monomers regardless of monomer structures and feed ratios. These copolymers have been determined to be highly transparent materials with high heat resistance (<i>T</i>_g: 130-190 °C), good thermal stability (<i>T</i>_d up to 300 °C), and good durability and are meanwhile fully degradable at room temperature under a strong base and completely thermal depolymerizable in the presence of a strong donating solvent (e.g., DMF), thus affording a new class of robust, durable, yet fully degradable, depolymerizable C-C main-chain polymers, which are generally unachievable due to an inherent performance/degradability (depolymerizability) trade-off.