Biomaterials Tutorial

Polytetrafluoroethylene (PTFE)

Felix Simonovsky
University of Washington Engineered Biomaterials                    

Polytetrafluoroethylene (PTFE) is a fluorocarbon-based polymer.  Commercially, the material is best known as Teflon® and Goretex®. It is made by free radical polymerization of tetrafluoroethylene and has a carbon backbone chain where each carbon has two fluorine atoms attached to it. 

This polymer is hydrophobic (water hating), biologically inert, non-biodegradable, and also has low friction characteristics and excellent “slipperiness.” The chemical inertness (stability) of PTFE is related to the strength of the fluorine-carbon bond.   This is why nothing sticks to this polymer. 

When stretched, PTFE forms a strong porous material called expanded PTFE (ePTFE). A commercial name for this form of Teflon in Goretex®.

Many popular products take advantage of the characteristics of PTFE polymer.  It has applications in medical, industrial, electronic, and performance fabric fields. As a medical material, PTFE has many uses, including arterial grafts, catheters, sutures, and uses in reconstructive and cosmetic facial surgery. 

PTFE can be fabricated in many forms, such as pastes, tubes, strands and sheets. ePTFE can be woven into a porous fabric-like mesh.  When implanted in the body, this strong mesh allows tissue to grow into its pores, making it ideal for medical devices such as vascular grafts.   Preformed PTFE subcutaneous implant materials have been used to improve facial reconstruction and cosmetic surgery outcomes. 

PTFE has relatively lower wear resistance. Under compression or in situations where rubbing or abrasion can occur, it can produce wear particles. These can result in a chronic inflammatory reaction, an undesirable outcome. For a given application, the biomaterials engineer must consider many aspects of the physical and biological properties of the materials. Thus, although PTFE is highly inert in the body, if applied in the wrong circumstances (for example, a device that is under compression or exposed to wear) it may lead to a reaction that no longer qualifies as “biocompatible.”

References:

Ratner BD, Hoffman AS, Schoen FJ, Lemons JE, editors.  Biomaterials Science: An Introduction to Materials in Medicine, 2nd ed.  London: Elsevier Academic Press; 2004.

Ngan V. Polytetrafluoroethylene Implants. DermNet NZ, July 2004. http://www.dermnetnz.org/procedures/polytetrafluoroethylene.html

About: The PTFE Story. W.L. Gore and Associates; 2004. http://www.gore.com/about/ptfe_story.html