Dual-selective polymerization: achieving chemoselectivity and stereoselectivity in a single catalytic system

The precise synthesis of multifunctional block copolymers with tailored architectures remains a pivotal challenge in polymer chemistry, particularly when balancing chemoselectivity and stereoselectivity within a single catalytic system. To address this challenge, we report the dual chemoselective and stereoselective capabilities of a commercially available chiral thiourea catalyst, (<i>S</i>,<i>S</i>)-TUC, for the synthesis of well-defined block copolymers. By leveraging its dual selectivity, (<i>S</i>,<i>S</i>)-TUC enables distinct polymerization pathways dictated by monomer composition. In the TMC/<i>rac</i>-LA system, stereoselective ring-opening polymerization (ROP) of <i>rac</i>-LA preferentially consumes D-LA to form PDLA blocks, followed by simultaneous ROP of TMC and L-LA, yielding pentablock copolymers. Conversely, in the PA/PO/<i>rac</i>-LA system, alternating copolymerization of PA and PO precedes stereoselective ROP of <i>rac</i>-LA, generating pentablock architectures. Comprehensive characterization (NMR, SEC, <i>in situ</i> IR, CD spectroscopy) confirms the catalyst's dual selectivity and adaptability. Notably, (<i>S</i>,<i>S</i>)-TUC operates under mild conditions, eliminates the need for multiple catalysts, and offers cost-effectiveness and low environmental toxicity. This work establishes a unified platform for synthesizing structurally complex copolymers, bridging the gap between precision polymerization and sustainable manufacturing. The methodology holds promise for applications in biodegradable materials, high-performance composites, and biomedical devices, where tailored polymer properties are critical.