Synthesis of fluorinated polyurethanes

Abstract

The purpose of this investigation is to develop LOX compatible adhesive systems which have structural utility at cryogenic temperatures. Work was concentrated on the preparation of fluorinated polyurethanes. Initial efforts were directed at highly fluorinated aliphatic and aromatic diamines. Several diamines were prepared and all were to be studied in their reaction with phosgene to prepare the corresponding diisocyanates. A unique chlorocarbonylation technique was developed for the synthesis of these fluorinated diisocyanates resulting in higher yields and less by-products than conventional phosgenation. Using a conventional approach to polyurethanes, highly fluorinated hydroxyl-terminated polyester and polyether oligomers were sought for reaction with the several isocyanates. Simple polymers were prepared and tested in LOX, three of which were shown to be LOX compatible. Efforts were made to determine structural effects on LOX compatibility.