PROCUREMENT OF PRIMARY REFERENCE MATERIALS

POLYURETHANES ARE USED IN A VARIETY OF BIOMEDICAL DEVICES, INCLUDING ARTIFICIAL HEARTS, VASCULAR GRAFTS AND CATHETERS, AND INTRA-AORTIC BALLOONS. THIS RESEARCH PRESENTS METHODS FOR SYNTHESIS, CHARACTERIZATION, AND FABRICATION OF POLY- URETHANEUREA (PUU) PRIMARY REFERENCE MATERIALS (PRM). THE PROGRAM INVOLVES THE SYNTHESIS OF A SINGLE LOT OF ADDITIVE- FREE POLYMER FOLLOWED BY THOROUGH CHARACTERIZATION OF THE BULK AND SURFACE PROPERTIES OF CAST FILMS. THE PUU WILL BE CONVERTED INTO TUBE AND SHEET CONFIGURATIONS UNDER CONTROL- LED AND DOCUMENTED CONDITIONS. BULK AND SURFACE PHYSIO- CHEMICAL CHARACTERIZATION WILL BE APPLIED TO ASSESS CHANGES INDUCED BY THE CONVERSION PROCESS, PACKAGING, AND STERILIZA-TION. A DOCUMENTATION PACKAGE WILL BE PROVIDED WITH THE PRMTHAT WILL CONTAIN THE CHARACTERIZATION RESULTS AND HANDLING AND STORAGE INSTRUCTIONS. DURING PHASE I, A LOT OF POLY- TETRAMETHYLENE (PTMO)-BASED PUU WILL BE SYNTHESIZED AND CHARACTERIZED. PILOT QUANTITIES OF PRM IN SHEET AND TUBING CONFIGURATIONS WILL BE FABRICATED TO ASSESS THE FEASIBILITY OF USING PUU AS REFERENCE MATERIALS. STERILE, PACKAGED SAMPLES WILL BE CHARACTERIZED TO DETERMINE THE EFFECT OF GAMMA RADIATION AND TO ASSESS TIME-DEPENDENT SURFACE CHANGESIN THE PRM. DURING PHASE II, PRM WILL BE FABRICATED FROM POLYETHYLENE OXIDE (PEO)-BASED PUU AND POLYDIMETHYLSILOXANE (PSX)-CONTAINING PUU TO PROVIDE PRM WITH A RANGE OF SURFACE FREE ENERGIES/HYDROPHOBICITIES. STERILE, PACKAGED SAMPLES OF THESE MATERIALS WILL BE CHARACTERIZED. SELECTED CHARAC- TERIZATION WILL BE CONDUCTED AT REGULAR INTERVALS TO DETERMINE IF THE BULK OR SURFACE PROPERTIES OF THE PRM HAVE AFFECTED BY STORAGE.