Polyester

Monomer

Organic chemistry

Polymer chemistry

Polycaprolactone

Caprolactone

Zinc

Engineering

Catalysis

Composite material

Molar mass

Chemistry

Materials science

Ring-opening polymerization

Lactide

Polymerization

Crystallinity

Chemical engineering

Biodegradable polymer

Polymer

Angewandte Chemie International Edition

Polylactide and polycaprolactone are both biodegradable polymers produced through metal‐catalyzed ring‐opening polymerization. For a truly sustainable lifecycle of these polymers it is essential to replace the industrially used cytotoxic catalyst tin(II) bis(2‐ethylhexanoate) [Sn(Oct) 2 ] with non‐toxic alternatives. Here, we report the fastest known robust catalyst in the polymerization of lactide and ϵ‐caprolactone. This zinc guanidine catalyst can polymerize non‐purified technical rac ‐lactide and ϵ‐caprolactone in the melt at different [M]/[I] ratios with fast rate constants, high molar masses, and high yields in a short time, leading to colorless, transparent polymer. Moreover, we report that polylactide and polycaprolactone produced by zinc‐guanidine complexes have favorably high crystallinities. In fact, the obtained polylactide shows a more robust degradation profile than its Sn(Oct) 2 ‐catalysed equivalent due to a higher degree of crystallinity.

Next Generation of Zinc Bisguanidine Polymerization Catalysts towards Highly Crystalline, Biodegradable Polyesters