LAUSR

A green synthetic route is proposed to obtain polyurethane with a controlled structure, by using maghnite-H+ as an environmentally friendly heterogeneous catalyst. The maghnite-H+ is an Algerian clay, characterized by very high specific surface. It was activated by an acid treatment leading to an increase of its interlayer space; this was clearly seen by X-ray diffraction analysis. The monomers used were 1,4-butanediol and hexamethylene diisocyanate; the polymerization was done without solvent and under mild operating conditions. The structure of the obtained polymer was characterized for various polymerization periods with infrared spectroscopy and 1H and 13C nuclear magnetic resonance. The change in average molecular mass and polydispersity index of the polymer was studied by gel permeation chromatography as a function of the time, temperature and mass content of catalyst. The operating conditions were optimized in such a way as to increase the yield of the reaction and to obtain a polymer of linear structure at the same time. Differential scanning calorimetry was used to measure the melting and glass transition temperatures of the polymer. Thermal stability was also studied by thermogravimetric analysis. The polymer obtained is a sponge capable of being deposited on paints for use in thermal insulation.