Exploiting Sodium Coordination in Alternating Monomer Sequences to Toughen Degradable Block Polyester Thermoplastic...

Area of Science:

• Materials Science
• Polymer Chemistry
• Sustainable Polymers

Background:

• Need for closed-loop recyclable thermoplastic elastomers (TPEs) in a circular economy.
• Limitations of current TPEs include degradation during recycling and reliance on hydrocarbon feedstocks.
• Development of advanced polymer architectures is crucial for sustainable materials.

Purpose of the Study:

• To synthesize and characterize novel, closed-loop recyclable block polyester TPEs.
• To investigate the impact of regularly placed ionic carboxylate side chains on material properties.
• To demonstrate the tunability of mechanical properties through controlled functionalization and ionization.

Main Methods:

• Controlled ring-opening polymerization to synthesize ABA block polyesters.
• Alternating ring-opening copolymerization for precise monomer sequencing.
• Post-polymerization functionalization to introduce carboxylic acid groups, followed by controlled ionization with sodium or lithium.

Main Results:

• Achieved high molar mass ABA block polyesters (60-100 kg mol^-1) with a defined block ratio.
• Ionized polymers exhibited significantly enhanced tensile strength (up to 20 MPa), elasticity (>2000%), and elastic recovery (>80%).
• A leading sample (2-COONa75) demonstrated recyclability (×3) via hot-pressing without property loss, and a wide operating temperature range (-52 to 129 °C).

Conclusions:

• Precisely controlled block polyester TPEs with ionic side chains offer superior mechanical performance and recyclability.
• The synthesis and functionalization strategies are generalizable to other monomers and metals, paving the way for diverse sustainable polymers.
• These partly bio-derived, degradable TPEs represent a promising advancement for sustainable material applications.