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, (S,S)-TUC, for the synthesis of well-defined block copolymers. By leveraging its dual selectivity, (S,S)-TUC enables distinct polymerization pathways dictated by monomer composition. In the TMC/rac-LA system, stereoselective ring-opening polymerization (ROP) of rac-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/rac-LA system, alternating copolymerization of PA and PO precedes stereoselective ROP of rac-LA, generating pentablock architectures. Comprehensive characterization (NMR, SEC, in situ IR, CD spectroscopy) confirms the catalyst's dual selectivity and adaptability. Notably, (S,S)-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.