Aliphatic Polyester Thermoplastic Elastomers Containing Hydrogen-Bonding Ureidopyrimidinone Endgroups.

Area of Science:

• Polymer Science
• Materials Science
• Sustainable Materials

Background:

• Polylactide-block-poly(γ-methyl-ε-caprolactone)-block-polylactide (LML) is a sustainable thermoplastic elastomer (TPE) with promising mechanical properties.
• Low glass transition temperature of polylactide endblocks leads to stress relaxation and poor elastic recovery in LML.
• Ureidopyrimidinone (UPy) moieties are hydrogen-bonding groups that can enhance polymer elasticity.

Purpose of the Study:

• To synthesize and characterize UPy-functionalized poly(γ-methyl-ε-caprolactone) (PMCL) and LML.
• To improve the elastic performance of LML by incorporating UPy endgroups.
• To investigate the effect of UPy functionalization on the mechanical properties and stress relaxation of LML.

Main Methods:

• Synthesis of UPy-functionalized PMCL and LML polymers.
• Characterization using mechanical testing (tensile strength, elongation at break, toughness).
• Stress relaxation studies at fixed strain to evaluate elastic recovery.

Main Results:

• UPy-functionalized PMCL did not exhibit elastomeric behavior at room temperature.
• UPy-functionalized LML showed increased ultimate tensile strength, elongation at break, and tensile toughness compared to unfunctionalized LML.
• UPy endgroups significantly reduced stress relaxation in LML, with further reduction observed when using semicrystalline poly((S,S)-lactide) endblocks.

Conclusions:

• UPy end-functionalization is an effective strategy to enhance the elastic performance of LML.
• The improved mechanical properties and reduced stress relaxation of UPy-LML make it a competitive sustainable TPE.
• Further improvements in elastic recovery can be achieved by incorporating semicrystalline endblocks with UPy functionalization.