Silyl ether-coupled poly(epsilon-caprolactone)s with stepwise hydrolytic degradation profiles

Area of Science:

• Polymer Chemistry
• Materials Science
• Biomaterials

Background:

• Poly(epsilon-caprolactone) (PCL) is a widely used biodegradable polyester.
• Controlling the degradation rate of PCL is crucial for advanced applications.
• Existing methods for PCL modification often lack precise control over degradation kinetics.

Purpose of the Study:

• To synthesize novel silyl ether-coupled PCLs with tunable, stepwise degradation profiles.
• To investigate the degradation mechanisms and kinetics of these new polymers.
• To establish a controlled degradation protocol for biomedical applications.

Main Methods:

• Synthesis of silyl ether-coupled PCLs via cross-dehydrocoupling polymerization of 1,4-bis(dimethylsilyl)benzene (BDSB) and diol-terminated PCL macromonomers.
• Catalysis using 10 wt % palladium on activated carbon in toluene at 100°C.
• Characterization using NMR spectroscopy (¹H, ¹³C, ²⁹Si), size exclusion chromatography (SEC), and differential scanning calorimetry (DSC).
• Hydrolytic degradation studies in solution monitored by SEC.

Main Results:

• Successfully synthesized silyl ether-coupled PCLs with controlled molecular weights (7590–29,900 g/mol).
• Demonstrated stepwise degradation: silyl ether linkages cleaved by acetic acid (half-life of 3 days), followed by PCL backbone degradation triggered by trifluoroacetic acid (half-life of 4 days).
• PCL segments released after silyl ether cleavage showed no significant degradation over 15 days.
• Achieved gradient degradation through a sequential acid treatment protocol.

Conclusions:

• Silyl ether-coupled PCLs provide a versatile platform for designing polymers with predictable, stepwise degradation.
• The developed sequential acid hydrolysis method allows for precise control over the degradation process.
• These findings open avenues for advanced applications in drug delivery, tissue engineering, and regenerative medicine.