SBIR-STTR Award

The goal of this study is to determine the feasibility of a novel method for modifying polymer surface properties without significant modification of their bulk properties. The modification is accomplished during synthesis by appending certain functional surface-active end groups onto polyurethanes. The products are essentially linear base polymers with covalently-bonded, 'surface-modifying end groups' (SME). A series of polyurethanes containing a variety Of SMEs will be synthesized. The surface-active end groups included in the proposed study are: polydimethylsiloxane, polyethyleneoxide, fluoroalkyl and alkyl sulfonate. The end groups are chosen to impart specific characteristics to the base polymer such as improved thromboresistance, biostability, abrasion resistance, etc. A variety of physicochemical characterization techniques will be used to assess the bulk and surface properties of the polymers. A quantitative model relating surface composition to bulk composition of the surface-modifying end groups will be developed and tested. In Phase II, SME polymers will be further evaluated for their blood and tissue compatibility. The use of surface-modifying end groups should facilitate the development and manufacture of a wide range of new and improved biomaterials which will be commercialized during Phase III.Proposed commercial application:These novel linear polymers are particularly suitable for use in the manufacture of medical devices, and especially of medical devices intended to be used in contact with bodily fluids such as blood. Examples of medical devices include catheters, vascular grafts, prosthetic heart valves and various blood pumps.National Institute of Heart, Lung, and Blood Institute (NHLBI)

The object of this study is to develop a manufacturing method for surface- modified thermoplastics using "surface modifying end groups" (SME). To date, the SME method has been used primarily with solution- processed segmented polyurethanes giving enhanced thromoboresistance, biostability and abrasion resistance in vitro and in vivo tests. In Phase I we used a series of surface sensitive analytical abrasion resistance in vitro and in vivo tests. In Phase I we used a series of surface sensitive analytical tools such as Sum Frequency Generation (SFG), Atomic Force Microscopy (AFM), Electron Spectroscopy for Chemical Analysis (ESCA) and Contact Angle Goniometry to fully characterize our polymers. Our studies have shown that SME technology could efficiently introduce a small fraction of end-groups covalently into polymer systems and dramatically change the surface chemistry of SME polymer surfaces. The region which end groups enrich in modulates biofunctionality and biocompatibility of implanted polymers. As the surface properties are changed dramatically by the end groups, bulk properties of polymers are virtually unaffected. To apply SME technology to do the broadest range of medical products, extrudable and moldable (i.e. thermoplastic) SME polymers are need in quantity. We are currently installing a production- scale continuous reactor-chiller pelletizer for conventional polyurethane manufacture. This study would support development, characterization, biocompatibility testing and validation of a process for the manufacture of a wide range of surface-modified polyurethane biomaterials. In Phase III SME theremoplastics of several types will be offered for sale to manufacturers of (chronically-implanted) devices and prostheses. PROPOSED COMMERCIAL APPLICATIONS: These novel polymer are intended for use in the manufacture of medical devices. They fill a need for materials having improved stability and biocompatibility in short and long term implantations. The market for unconfigured biomedical polymers and components of this type exceeds $100 million annually. The sale of devices with using these polymers could exceed $1 billion annually.