Toward regulating biodegradation in stages of polyurethane copolymers with bicontinuous microphase separation

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Materials Engineering

Background:

• Biodegradable polymers typically show performance decline with degradation, creating a dilemma between service life and environmental retention.
• Developing biodegradable devices with stable in-service performance and rapid post-service degradation is a significant challenge.

Purpose of the Study:

• To engineer biodegradable polymers with controlled, staged degradation for improved device performance and environmental fate.
• To synthesize and characterize polyurethane copolymers (PCL-b-CrP-U) with distinct microphase degradation rates.

Main Methods:

• Synthesis of polyurethane copolymers (PCL-b-CrP-U) comprising poly(ε-caprolactone) (PCL) and random copolymer (CrP) blocks.
• Alkali-accelerated degradation experiments to study morphology and self-reinforcement mechanisms.
• Tensile testing to evaluate mechanical properties.
• Degradation studies in artificial pancreatic juice to assess staged degradation behavior.

Main Results:

• PCL-b-CrP-U exhibits excellent mechanical properties, including 1500% elongation at break.
• Degradation in artificial pancreatic juice shows a three-stage process: induction, steady, and accelerated.
• Amorphous CrP phase hydrolysis creates microchannels, enhancing water/enzyme penetration.
• Crystallization of PCL segments during degradation forms a reinforcing scaffold, maintaining mechanical stability.

Conclusions:

• The bicontinuous microphase strategy enables staged degradation of biodegradable polymers.
• The self-reinforcing scaffold structure ensures stable mechanical performance during the steady degradation phase.
• Rapid degradation of residues is facilitated by the scaffold morphology, preventing long-term environmental retention.