Conditioning polytetrafluoroethylene surfaces for use in vascular prostheses

Abstract

AbstractPolytetrafluoroethylene surfaces have been treated to reduce thrombogenicity in order to make them suitable for use in prosthetic devices that come in contact with blood. This was done by first etching the surface with potassium in liquid ammonia to produce double bonds and then using these double bonds as sites for grafting on polyacids or as sites for chemical reactions. Tubes so treated were tested for thrombo‐genetic activity by implantation in the thoracic aorta or inferior vena cava of dogs. These tests showed that the thrombogenicity of a polytetrafluoroethylene surface can be reduced by attaching negatively charged groups provided the surface concentration of these groups is not too high (order of 1–2 × 10−6 equivalent per cm2 geometric area) and provided the distribution of these groups is uniform. Sulfonic acid groups obtained by chlorosulfonation and carboxyl groups attached by grafting tert‐butyl crotonate and hydrolyzing to crotonic acid were effective. Long chains of poly(acrylic acid), poly‐(ethylenesulfonic acid), and poly(vinyl alcohol) sulfate were less effective.