Schiff based derived homogeneous catalysts for ring‐opening terpolymerization

In this study, we synthesized and evaluated a series of Schiff base cobalt catalysts for the terpolymerization of propylene oxide, l ‐lactide and carbon dioxide. The catalytic system leverages the Lewis acid cobalt centre to activate the monomers, promoting chain propagation while minimizing undesirable backbiting reactions that lead to cyclic byproducts. To systematically modulate the electrophilicity of cobalt, four Schiff base complexes were designed with electronic modifications, including para‐chlorine substituents and axial pentafluorobenzoate groups, to fine‐tune electron density at the metal centre. Structural characterization via Fourier Transform Infrared Spectroscopy, NMR Spectroscopy and High‐Resolution Mass Spectrometry confirmed the successful synthesis and coordination of the initiators, with electronic variations influencing their catalytic behaviour. Among various catalyst combinations tested, the system comprising Initiator‐2, Initiator‐4 and bis(triphenylphosphine)iminium chloride in an equimolar ratio exhibited the highest efficiency, yielding a high molecular weight polymer ( M n = 61 362 g mol –1 , M w = 123 996 g mol –1 ) with a dispersity ( Ð ) of 2.02. This study provides crucial insights into the structure–property relationships governing Schiff base initiated terpolymerization, highlighting the role of ligand electronics in dictating polymerization activity, selectivity and product distribution. The optimized catalyst design presents a rational strategy for developing efficient and selective catalytic systems for sustainable polymer synthesis.