Heterobimetallic Janus Catalysts for the One‐Pot Synthesis of Polar‐Apolar Block Copolymers

ABSTRACT

The one‐pot synthesis of apolar‐polar block copolymers combining polyolefins with polyesters has been a long‐standing challenge in polymer chemistry. Despite broad‐reaching applications of apolar‐polar block copolymers in drug delivery, compatibilisation of polymer blends and biomedical materials, their synthesis often requires multi‐step protocols with multiple catalysts and several isolation and purification steps. This is a particular challenge when combining the polymerisation of non‐activated α‐olefins with lactones, as these two distinct polymerisation mechanisms are often incompatible. This work reports heterobimetallic Janus catalysts for orthogonal 1‐hexene and ε‐caprolactone polymerisation. Generated in situ, the active catalysts combine distinct Ti and Al metal centres connected by a Ti‐C(H)═C(R)CH ₂ O‐Al linker (R = Me or Bn). This approach successfully delivered poly(1‐hexene)‐ block ‐poly(ε‐caprolactone) copolymers with well‐controlled linear block copolymer architectures, targeted molar compositions and tuneable molar mass ( M _n values < 67.3 kDa, Ð = 1.47), in a one‐pot reaction, an approach that was successfully extended to poly(1‐octene)‐ block ‐poly(ε‐caprolactone) and poly(1‐decene)‐ block ‐poly(ε‐caprolactone) copolymers. Overall, this work is a notable addition to the toolbox for synthesising apolar‐polar block copolymers. This work demonstrates for the first time that titanium‐alkenyl complexes can efficiently initiate olefin polymerisations and that heterobimetallic complexes can act as efficient bifunctional initiators for distinct polymerisation mechanisms.