Aluminum Porphyrin Complex Mediated Auto-Tandem Catalysis for One-Pot Synthesis of Block Copolymers

Auto-tandem catalysis that uses a single catalyst to bridge and discriminate different catalytic cycles in a one-pot process is highly desirable for obtaining a high degree of structural complexity; however, it is a great challenge to develop auto-tandem catalytic systems in polymer chemistry. Herein, we report the auto-tandem catalysis by rationally designed aluminum porphyrin complexes, wherein well-controlled photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization of vinyl monomers and completely alternating ring-opening copolymerization (ROCOP) of epoxides/anhydrides can occur in a concurrent or sequential manner. With a carboxylic group incorporated trithiocarbonate compound bearing a carboxylic acid group (TTC-COOH) as the bifunctional chain transfer agent (CTA), the auto-tandem catalysis provides one-pot access to diblock copolymers with predictable molecular weights and narrow distributions. Notably, the efficient electron/energy transfer from 5,10,15,20-tetrakis(2-chlorophenyl) porphyrin aluminum(III) chloride [(TPP2-Cl)Al-III-Cl] to TTC-COOH and their axial group exchange reactions completely circumvent the formations of undesirable homopolymers. [GRAPHICS] .

Automated summary

This study reports an auto-tandem catalytic reaction initiated by aluminum porphyrin complexes, which allows concurrent or sequential polymerization and copolymerization reactions to obtain diblock copolymers with controlled molecular weights and narrow distributions.