Chemical stability of polyether urethanes versus polycarbonate urethanes

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Chemical Engineering

Background:

• Pellethane is a widely used polyetherurethane in biomedical devices.
• Corethane, a polycarbonate urethane, is a potential alternative biomaterial.
• Assessing material stability in physiological environments is crucial for biomedical applications.

Purpose of the Study:

• To compare the chemical stability of Pellethane and Corethane under various aging conditions.
• To characterize the chemical modifications induced by hydrolytic, oxidative, and physiological media.
• To determine the suitability of these polyurethanes for biomedical applications.

Main Methods:

• Aging protocols simulating hydrolytic, oxidative, and physiological conditions (water, H2O2, nitric acid, buffer, lipid, bile).
• Characterization techniques: Differential Scanning Calorimetry (DSC), Gel Permeation Chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR).
• Analysis of molecular weight changes, thermal properties, phase separation, and surface modifications.

Main Results:

• Both polymers showed mild hydrolysis and molecular weight loss, except in nitric acid.
• Pellethane exhibited phase separation and increased order in soft/hard segments when aged in water/H2O2.
• Corethane demonstrated uniform molecular reorganization and phase separation, with less chain scission in nitric acid than Pellethane.
• Lipid adsorption was observed on Corethane after 120 days in bile.

Conclusions:

• Polycarbonate urethane (Corethane) exhibits superior chemical stability compared to polyetherurethane (Pellethane).
• Corethane's structural integrity and resistance to degradation make it a promising candidate for biomedical applications.
• Understanding polymer degradation mechanisms is vital for designing durable and safe biomaterials.