Crystallization and Stereocomplexation of PLA-mb-PBS Multi-Block Copolymers

Area of Science:

• Polymer Science
• Materials Science
• Crystallography

Background:

• Polylactic acid (PLA) and polybutylene succinate (PBS) are biodegradable polymers with distinct properties.
• Copolymerization offers a route to tailor material characteristics.
• Stereocomplexation in PLA can enhance thermal and mechanical properties.

Purpose of the Study:

• Investigate the crystallization behavior of PLA-mb-PBS copolymers.
• Determine the effect of PBS flexible blocks on PLA crystallization and morphology.
• Analyze the impact of PBS on stereocomplex formation between PLLA and PDLA segments.

Main Methods:

• Polarized light optical microscopy (PLOM) for morphology.
• Differential scanning calorimetry (DSC) for thermal analysis.
• Infrared spectroscopy (FTIR) and ¹³C-NMR for structural and stereocomplex analysis.

Main Results:

• PLA and PBS blocks are miscible in melt and glassy states.
• PLA crystallizes first, forming superstructures that template PBS crystallization.
• PBS segments hinder stereocomplexation, with an initial enhancement at low concentrations, followed by suppression at higher concentrations.

Conclusions:

• The crystallization kinetics and morphology of PLA-mb-PBS copolymers are governed by the interplay between PLA and PBS blocks.
• PBS chain segments significantly influence stereocomplex formation, acting as a disruptor at higher contents.
• Controlled addition of PBS may offer a method to tune stereocomplexation in PLA-based materials.