| abstract |
A microporous biocompatible material is formed by preparing a segmented polyether urethane urea solution containing 25%±1.5% solids dissolved in a solvent. The solution has sufficient viscosity to be preshaped and formed into the desired thickness of the finished article, then immediately immersed into a precipitation bath in which the solvent in the solution is miscible for a time interval sufficient to cause the solution to set up into an opaque elastomeric article. The article is immediately removed from the bath, any excess solvent extracted and then dried at a temperature on the order of 35° C. to 70° C. followed by heat treating by annealing for approximately sixty minutes at a temperature at 100° C. to 130° C. The void volume of the membrane solution is controlled to within the 50% to 80% range and the pore size from ca <0.1 to several mms. as well as the shape of the pores and solid structures between them, thereby enabling close control over the characteristics and structure of the material as well as over variations in structural characteristics and porosity across the thickness of the material according to its intended application and use. |