Highly Cross-Linked Shape Memory Polymers with Tunable Oxidative and Hydrolytic Degradation Rates and Selected...

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Medical Device Engineering

Background:

• Shape memory polymers (SMPs) are promising for minimally invasive medical devices.
• Existing porous SMPs exhibit oxidative degradation, but incorporating hydrolytic degradation often compromises thermal properties.
• Rapidly decreasing glass transition temperature (T_g) hinders strain fixity at body temperature.

Purpose of the Study:

• To synthesize and incorporate ester networks into SMPs to control morphology and degradation.
• To investigate the impact of ester networks on the glass transition temperature (T_g) and degradation profiles.
• To develop SMPs with tunable dual hydrolytic and oxidative degradation for biomedical applications.

Main Methods:

• Synthesized ester networks via esterification of triethanolamine.
• Incorporated ester networks into SMPs to modify bulk morphology.
• Evaluated T_g to ensure it remained above 37 °C.
• Assessed degradation rates through oxidation and hydrolysis over 140 days.

Main Results:

• Ester networks maintained T_g above 37 °C even with 50% ester contribution.
• Synthesized SMPs exhibited dual hydrolytic and oxidative degradation.
• Oxidative degradation rate increased significantly after 30 days (0.2%/day to 3.5%/day).
• Control materials degraded slowly (0.2%/day) over 140 days, losing ~30% mass.

Conclusions:

• Ester-modified SMPs provide a viable method for controlling morphology and achieving tunable degradation.
• These SMPs demonstrate potential for creating rapidly degradable, soft, porous biomaterials.
• The developed material system shows promise for advanced medical device applications requiring controlled degradation.