Modification chimique du polybutadiene-1,2 par le phosphonate d'éthyle

The addition of diethyl phosphonate [HPO(OEt)₂] (I) to carbon-carbon double bonds of 1,2-polybutadiene is studied, in order to obtain functionalised polymers with phosphonate pendent groups. The interest is to obtain structures soluble in organic solvents, such as benzene or chloroform. The reaction is mainly catalysed by peroxides, tert.-butyl hydroperoxide being the most efficient. Study of the influence of various parameters (temperature, solvent and catalyst nature, concentrations of the various reaction components) has shown that the addition competes with cyclisation and, mostly, cross-linking reactions. (I) Addition and reticulation rates are closely dependent: increase of the first is always accompanied by increase of cross-linking. Whatever the reaction conditions may be with the considered 1,2-polybutadiene, gelation is complete as soon as the modification yield exceeds 6%. The polymer structures have been studied by ¹H-NMR and i.r., by comparison with those of the addition compounds obtained with model molecules (3-ethyl 1-pentene, 4-octene, 1,6-heptadiene).