Poly(urethane-methacrylate)s. Synthesis and characterization

A series of poly(ester-urethane-urea)s containing pendant methacrylate func tionality has been prepared, characterized and formulated into polyurethane methacrylate elastomers using a prepolymer process. Poly(ester-urethane-me thacrylate)s were polymerized in a two-step process: synthesis of an isocya nate terminated prepolymers prepared from an excess molar concentration of 4,4 ' -methylene diphenyl diisocyanate with poly(ester)diols [Mn similar to 2000] and reaction the product with hexamethylenediamine and neutralizatio n with methacrylic. In general, these materials exhibit physical properties similar to those of linear segmented polyurethanes rather than conventional thermal or radiati on-cured oligomer based on polyurethane methacrylates. The cured materials were characterized by IR, stress-strain, thermogravimet ric and thermally stimulated depolarization current experiments. Properties were compared to a polyurethane elastomer control in which the variable wa s the polyester diols' modification. The polyester diols modification produ ces polymers with decreased modulus, tensile strength, elongation. The cros slinking process depresses crystallization of the soft segments and improve s tensile properties and can obtain protective films and finish materials f or leather industry. Introducing diamine and methacrylic structural units extends the hard ureth ane segments. (C) 2001 Elsevier Science Ltd. All rights reserved.