Properties of polyurethanes derived from poly(diethylene glycol terephthalate)

The synthesis of linear and crosslinked polyurethanes based on α,ω-dihydroxypolydiethylene glycol terephthalate (PDET) is described. Prior to the preparation of these materials, a PDET polymer was obtained by conventional condensation reaction between dimethyl terephthalate and diethylene glycol, and a well-characterized fraction of PDET with number average molecular weight of 3,650 g mol−1 was chosen for the synthesis of the polyurethanes. Specifically, three polyurethanes were prepared: a pure linear polyurethane by reaction of PDET with 4,4′-diphenylmethane diisocyanate (MDI), a chain extended polyurethane obtained with MDI, PDET and 1,4-butanediol as chain extender, and a crosslinked polyurethane synthesized from PDET and a polyfunctional isocyanate. Thermal, mechanical, dielectric and gas transport properties of the polyurethanes were studied, showing excellent performance. In particular, rubber-like flexible materials were obtained with elongation values over 1000%, due to the low glass transition temperature of PDET. Furthermore, it was observed that these materials, in particular the crosslinked polyurethane, behave as gas barriers.

Ángel Marcos Fernández, Rodrigo Navarro, Esperanza Benito, Julio Guzmán, Leoncio Garrido.