SYNOPSISNew fluorinated thermoplastic elastomers (FTE) with perfluoropolyether (PFPE) blocks have been synthesized by reacting a fluorinated macrodiol with aromatic diisocyanates in the presence of a solvent, followed by subsequent chain extension with low molecular weight aliphatic or aromatic diols. Tensile properties measurements and dynamical-mechanical analysis (DMA) have been carried out and the relationship between chemical structure and final properties has been determined. These new thermoplastic fluorinated polyurethanes show an elastomeric behavior over a wide temperature range (between -75 and lOO"C), thanks to their multiphase morphology consisting of a continuous fluorinated phase with a very low T, (-120°C) and a dispersed high melting hydrogenated hard phase, as verified by a calorimetric and dynamic-mechanical analysis. At the same time, some of the outstanding properties of fluorinated oligomers, such as chemical inertness and low surface tension, are retained in the final polymers. Thanks to these characteristics this new class of polymeric materials provides new opportunities for the application of thermoprocessable elastomers in advanced technological fields. 0 the soft segments or their crystallization tendency; this makes conventional polyurethanes unsuitable for temperatures lower than -40°C.PUTEs are block copolymers in which the soft segments are based on polyester or polyether chains; the polyester types offer some advantages in terms of mechanical properties, high-temperature performance, and thermal stability, while the polyetherbased materials have better resistance to hydrolysis and exhibit low-temperature elastomeric behavior (when relatively high molecular weight polyether diols areOn the basis of these considerations it seems attractive to develop new PUTEs offering the basic advantages of thermoplastic elastomers and exhibiting a lower Tg of the elastomeric block, adequate tensile properties, improved chemical resistance, and a lower surface tension. In principle, these improvements should be achievable by introducing fluorinated blocks into the polymer chains. As a matter of fact, thermoplastic fluoropolymers are commercially succesful thanks to their unique balance of properties, such as low surface energy, low coefficient of friction, nonflammability, low dielectric constant, and high solvent and chemical resistance.'l 311

New segmented polyurethanes (FPU) with perfluoropolyether (PFPE) blocks have been synthesized by a two‐step process. In the first step, a fluorinated isocyanate end‐capped prepolymer has been obtained by reaction of a fluorinated macrodiol with alicyclic diisocyanates in the presence of solvent. The following chain extension has been carried out by reaction of the prepolymer with short hydrogenated polyols giving a polymeric matrix. Tensile properties, dynamical–mechanical (DMA), and calorimetric (DSC) analyses have been evaluated, and relationships between chemical structure and final properties are established. These polymers show unusual low‐temperature elastomeric behavior, due to the low glass transition (Tg) of the continuous fluorinated phase. In general, with respect to traditional polyurethanes (HPU), thermal stability and chemical resistance are strongly improved by the effect of the highly inert fluorinated chains. © 1995 John Wiley & Sons, Inc.

SYNOPSISNew fluorinated thermoplastic elastomers (FTE) with perfluoropolyether (PFPE) blocks have been synthesized by reacting a fluorinated macrodiol with aromatic diisocyanates in the presence of a solvent, followed by subsequent chain extension with low molecular weight aliphatic or aromatic diols. Tensile properties measurements and dynamical-mechanical analysis (DMA) have been carried out and the relationship between chemical structure and final properties has been determined. These new thermoplastic fluorinated polyurethanes show an elastomeric behavior over a wide temperature range (between -75 and lOO"C), thanks to their multiphase morphology consisting of a continuous fluorinated phase with a very low T, (-120°C) and a dispersed high melting hydrogenated hard phase, as verified by a calorimetric and dynamic-mechanical analysis. At the same time, some of the outstanding properties of fluorinated oligomers, such as chemical inertness and low surface tension, are retained in the final polymers. Thanks to these characteristics this new class of polymeric materials provides new opportunities for the application of thermoprocessable elastomers in advanced technological fields. 0 1996 John Wiley & Sons, Inc.

The thermal reactivity of a set of different blocked perfluoropolyether (PFPE) containing polyisocyanates and one monocomponent polyurethane containing a PFPE diol was investigated by Fourier transform infrared (FT-IR) spectroscopy. With the former series of products the deblocking kinetics at 90 degrees C and 120 degrees C were investigated with time-dependent spectral data, showing the highest thermal deblocking activity for 3,5 dimethylpyrazole blocking agent. The crosslinking reaction of the PFPE diol with ketoxime blocked isocyanurate at 150 degrees C was monitored by infrared (IR) spectroscopy and two-dimensional (2D) correlation analysis; the results suggested a prevailing direct condensation mechanism and the formation of urea byproducts in the later stages of reaction. Both synchronous and asynchronous spectra were considered and discussed, pointing out the time relation of the chemical functions during the crosslinking experiment.

New fluoropolyether polyolic resins are presented suitable to be cured with conventional hardeners as polyisocyanates or melamines. These resins are prepared by addition of fluoropolyether macrodiols (Fomblin@ ZDOLTX) of various molecular weights to isophorone diisocyanate (IPDI) to give oligomeric NCO-terminated prepolymers. The final hydroxy functionality is obtained by the reaction of those prepolymers with trimethylolpropane (TMP). The viscosity of the resins is measured at various concentrations (weight fraction 0.8 -0.4) and temperatures (T = 25 -65 "C). The results are discussed in terms of the Erickson equation (q vs. concentration) and using the WLF and Arrhenius models (q vs. T). The thermal behavior is studied by DSC for both the resins and cured films indicating the presence of two T,s, corresponding to the segregated fluorinated and hydrogenated phases, the former particularly evident with the highest molecular weights of the fluorinated macromer. Tensile curves of selfsupported films are then analyzed showing an evident tough-plastic behavior especially for the isocyanate-cured films. The application of such materials as high-durability clear coats is finally proposed. ZUSAMMENFASSUNG:Neuartige Fluoropolyether-Polyol-Harze, die mit konventionellen Hartern wie Polyisocyanaten oder Melaminen aushartbar sind, wurden hergestellt . Zunachst wurden oligomere NCO-terminierte Prepolymere durch Addition von Fluorpolyether-Makrodiolen unterschiedlicher Molekulargewichte an Isophorondiisocyanate erhalten. Durch die Reaktion dieser Prepolymeren mit Trimethylolpropan wurden endstandige Hydroxygruppen eingefuhrt. Die Viskositat von Ldsungen dieser Harze wurde bei unterschiedlichen Konzentrationen (Massenbruch 0,4 -0,8) und Temperaturen (25 "C-65 "C) gemessen. Die erhaltenen Werte wurden auf der Basis der Erickson-Gleichung (Konzentrationsabhangigkeit von q) und unter Berucksichtigung des WLFund des Arrhenius-Modells (Temperaturabhangigkeit von q) diskutiert. Das thermische Verhalten der Harze und von ausgeharteten Filmen wurde mit DSC bestimmt.