Star-shaped PHB-PLA block copolymers: immortal polymerization with dinuclear indium catalysts

Area of Science:

• Polymer Chemistry
• Materials Science
• Organic Synthesis

Background:

• Star-shaped polymers offer unique properties compared to linear counterparts.
• Controlled synthesis of complex polymer architectures is crucial for advanced materials.
• Existing methods for synthesizing star-shaped polyesters are limited.

Purpose of the Study:

• To report the first one-component precursor for star-shaped polyesters.
• To synthesize novel star-shaped poly(hydroxybutyrate)-poly(lactic acid) block copolymers.
• To investigate the catalytic activity and polymerization mechanisms of novel complexes.

Main Methods:

• Synthesis and full characterization of mono- and bis-benzyl alkoxy-bridged complexes.
• Investigation of solvent-dependent solution structures and reactivity.
• Controlled ring-opening polymerization of beta-butyrolactone (BBL) and lactide (LA).
• Study of immortal polymerization and copolymerization in the presence of alcohols.

Main Results:

• Novel one-component precursors for star-shaped polyesters were successfully synthesized.
• The complexes demonstrated high catalytic activity for controlled polymerization of BBL at room temperature.
• Solution studies revealed mononuclear propagating species in THF, with dimer-monomer equilibrium influencing BBL polymerization rates.
• Well-controlled immortal polymerization and copolymerization of BBL and LA were achieved.

Conclusions:

• A new synthetic route to star-shaped poly(hydroxybutyrate)-poly(lactic acid) block copolymers has been established.
• The developed complexes are highly effective catalysts for controlled and immortal polymerization.
• Understanding the solution behavior of the catalysts is key to controlling polymerization kinetics.