Etude cinktique du greffage de polystyrhe anionique sur les silices Contraction des macromolkcules sur la surface solide Par EUGSNE PAPIRER et VAN TAO NGUYEN (Eingegangen am 12. Juni 1972)
Polystyrene or polystyrene–polyisoprene copolymers have been grafted onto silica by an anionic procedure. The solvent resistance of the grafts has been examined. Linear relationships between the extractable amount of polymer and the solvent extraction temperatures are observed. The extrapolation of these lines leads to temperatures that are in close agreement with the ceiling temperatures of the grafted polymers.
Anionic grafting of polyisoprene and polystyrene by desactivation of a living polymer on the ester groups previously introduced on the carbon black surface has been followed as a function of the molecular weight of the polymer. The desactivation reaction is limited. A correlation between the grafting ratios and the molecular weights exists. If we assume the macromolecule to behave like spheres having a radius identical to the gyration radius calculated from the viscosity measurement, we will be able to determine the surface coverage of the solid sample. A constant value equal to 1,5 is thus obtained for all the polymers having molecular weights ranging from 4000 to 135000. A surface coverage of 1 would correspond to ellipsoids showing axes ratios in close agreement with those calculated statistically by KUHN.
RESUME :Nous avons 6tudi6 le greffage anionique de polyisoprhe et de polystyrhe par desactivation d'un polymere ,,vivant" sur un noir de carbone porteur de groupements ester methylique. Le taux de greffage est suivi en fonction des masses moleculaires du polyisopr&ne greffe. I1 apparait que la reaction est limithe par la dimension de la macromol6cule. En admettant une configuration spherique du polyiso-pr6ne it la surface du noir de carbone, on peut calculer it partir du rayon de giration determine sur l'homopolym8re en solution, un taux de recouvrement de la surface solide. Ce taux est constant et voisin de 1,5 pour l'ensemble des polyisoprhes dont les masses moleculaires varient entre 4000 et 135000. De plus, en determinant les rapports des axes des ellipsoides ayant les m6mes volumes que les spheres limites, mais dont la section la plus petite conduit it la formation d'une monocouche, on retrouve les valeurs calculees statistiquement par KUIIN. Un taux de recouvrement Bgal it 1 pourrait aussi &re obtenu en admettant une interpenetration mutuelle des pelotes spheriques en surface du noir de carbone.
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