Stereocomplexation of Stereoregular Aliphatic Polyesters: Change from Amorphous to Semicrystalline Polymers with...

Area of Science:

• Polymer Chemistry
• Materials Science
• Stereochemistry

Background:

• Stereocomplexation enhances polymer properties via co-crystallization of chiral polymer strands.
• Biodegradable polyester stereocomplexes, excluding PLA, are underexplored.
• The link between polymer microstructure and stereocomplexation, especially in chiral copolymers, needs clarification.

Purpose of the Study:

• To investigate stereocomplexation in novel biodegradable polyesters.
• To explore the impact of chiral building block combinations on polymer microstructure and properties.
• To develop semicrystalline copolymers with enhanced thermal stability through stereocomplexation.

Main Methods:

• Resolution of enantiomers for a non-symmetric chiral anhydride (CPCA).
• Metal-catalyzed ring-opening copolymerization (ROCOP) to prepare polyesters from various chiral epoxides and anhydrides.
• Preparation of stereocomplexes by mixing equimolar amounts of enantiomeric copolymers.

Main Results:

• Specific chiral combinations of epoxide and anhydride monomers induced semicrystallinity.
• A single stereocenter inversion altered copolymer crystallinity from amorphous to semicrystalline.
• Stereocomplexes exhibited increased melting temperatures (approx. 20 °C higher) compared to enantiopure counterparts.
• Optimized stereocomplex achieved a high melting temperature of 238 °C.

Conclusions:

• Chiral selection in monomer building blocks is critical for achieving semicrystalline biodegradable polyesters via ROCOP.
• Stereocomplexation of these novel copolymers significantly enhances thermal properties.
• This work provides a new strategy for designing high-performance biodegradable polymers with tailored microstructures.