NEW PERFLUOROPOLYETHER SOFT SEGMENT CONTAINING POLYURETHANES

New segmented polyurethanes (FPU) with perfluoropolyether (PFPE) block s have been synthesized by a two-step process. In the first step, a fl uorinated isocyanate end-capped prepolymer has been obtained by reacti on of a fluorinated macrodiol with alicyclic diisocyanates in the pres ence of solvent. The following chain extension has been carried out by reaction of the prepolymer with short hydrogenated polyols giving a p olymeric matrix. Tensile properties, dynamical-mechanical (DMA), and c alorimetric (DSC) analyses have been evaluated, and relationships betw een chemical structure and final properties are established. These pol ymers show unusual low-temperature elastomeric behavior, due to the lo w glass transition (T-g) of the continuous fluorinated phase. In gener al, with respect to traditional polyurethanes (HPU), thermal stability and chemical resistance are strongly improved by the effect of the hi ghly inert fluorinated chains. (C) 1995 John Wiley and Sons, Inc.