Use of surface-modifying macromolecules to enhance the biostability of segmented polyurethanes

✍ Scribed by Tang, Y. W. ;Santerre, J. P. ;Labow, R. S. ;Taylor, D. G.

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 276 KB
• Volume: 35
• Category: Article
• ISSN: 0021-9304
• DOI: 10.1002/(sici)1097-4636(19970605)35:3<371::aid-jbm11>3.0.co;2-i

✦ Synopsis

Polyurethanes are widely used as biomaterials for medical implants because of their excellent mechanical properties and moderate biocompatibility. However, the demand for more bioresistant and biocompatible polyurethanes to meet the needs of long-term implant devices still remains an important issue. Since most biological interactions with materials occur at the interface, a significant number of studies for improving the biocompatibility of polyurethanes have concentrated on surface modification. It is well known that additives used in polymeric materials as processing aids, mold releasing agents, antioxidants, etc., migrate to the surface and change the surface properties of the material. Under certain conditions polymeric additives may also migrate toward surfaces. This study describes two fluorinecontaining, surface-modifying macromolecules (SMMs) that have been evaluated for their ability to inhibit polyurethane degradation. These materials actively migrate to the upper surface of a material film when they are mixed with a base polymeric material. Contact angle measurements for the mixture of SMM with base polyurethane indicate that the surface becomes more hydrophobic after adding the SMMs, while X-ray photoelectron spectroscopy analysis shows an enrichment of fluorine on the polymer surfaces. Differential scanning calorimetry thermograms indicate that the microstructure, as defined by the thermal transitions of the base polymer, are not altered by the addition of SMMs. Enzymeinduced biodegradation tests exhibit a significant reduction of polyurethane degradation in the presence of these surface-resident materials. The results indicate that the SMMs have the potential to resist hydrolytic degradation mediated by lysosomal enzymes while generating a surface chemistry on the native elastomer which is similar in nature to that of a fluoropolymer, e.g., Teflon.