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.

A family of anionomeric segmented polyurethane-ureas made from ␣-dimethylol-terminated perfluoropolyethers (M n ϭ 1000 -2000), isophorone diisocyanate, dimethylol propionic acid, and ethylenediamine was obtained in form of stable aqueous dispersions. The dispersions were characterized by viscometry and dynamic laser light scattering. The main compositive parameters explored were the amount of COOH groups and the length of the fluorinated macromer. The new polyurethane-ureas were characterized by dynamic mechanical analysis obtaining information on modulus, thermal transition, and phase segregation. Surface properties and chemical resistance were estimated through measurements of static contact angles and spot tests with different solvents. Although surface hydrophobicity was not affected by composition, water-sorption behavior was sensitive to the ionic character (COOH level) of the polymer. Diffusion and permeability coefficients of polymer films, having different carboxyl contents, were estimated.

Three model structures of linear segmented anionomeric polyurethanes based on perfluoropolyether dimethylol-terminated oligomers, isophorone diisocyanate, and dimethylol propionic acid were synthesized and obtained in the form of aqueous dispersions. The structures differed from each other in the chemical nature of the chain extender (diol or diamine) and in the content of carboxylic acid. Dispersions and polymer films were characterized by dynamic light scattering, dynamic mechanical analysis, differential scanning calorimetry, and contact angle measurements. Diluted aqueous dispersions were also evaluated as protective sizing agents in paper treatment, both as bulk modifiers and as surface treatments. Paper sheets characterized by high water and oil repellence were obtained. The results showed that performance is mainly related to the ionic group content of the polymer and to its molecular architecture.

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.