DETERMINATION OF LOW CRITICAL SURFACE TENSIONS OF NOVEL FLUORINATED POLY(AMIDE URETHANE) BLOCK-COPOLYMERS .1. FLUORINATED SIDE-CHAINS

Low critical surface energies of novel fluorinated poly(amide urethane ) block copolymers were measured. The copolymers contain a ''hard bloc k'' polyurethane consisting of a diisocyanate and a diol and a ''soft block'' non-self-associating polyamide consisting of oligomers synthes ized from fluorinated secondary diamines and adipoyl chloride. The var ious diisocyanates studied were methylenebis(phenylene isocyanate) (MD I), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), and me thylenebis(cyclohexane isocyanate) (H(12)MDI). Butanediol and hexanedi ol were the diols used. The different diamines studied were N,N'-diiso propyl-1,6-diaminohexane, ifluoroethyl)-1,6-diaminohexane-1,6-diaminoh exane, is(3,3,3,2,2-pentafluoropropyl)-1,6-diaminohexane, ,N'-bis(1H,1 H-heptafluorobutyl)-1,6-diaminohexane, and N,N'-bis(1H, 1H-perfluorooc tyl)-1,6-diaminohexane. The critical surface tensions of the poly(amid e urethane) block copolymers were determined with Zisman plots using c ontact angle goniometry, and water contact angles were obtained by bot h goniometry and-the Wilhelmy method. Intrinsic viscosities and therma l transitions were determined. The large hysteresis seen in the contac t angle measurements and the kinetic instability of water drop shapes on polymer films indicate that although the air-polymer interface show s a fluorinated surface, exposure to water can effect a rearrangement allowing exposure of a more polar entity.