SYNTHESIS AND BEHAVIOR OF THE POLYMER COVERING ON A SOLID-SURFACE - 3- MORPHOLOGY AND MECHANISM OF FORMATION OF GRAFTED POLYSTYRENE LAYERSON THE GLASS-SURFACE

Polystyrene films have been grafted by radical polymerization in situ on the surface of glass slides. The morphology of these films resultin g from different grafting temperatures has been investigated by both t he contact angle method and scanning probe microscopy with respect to the grafting time. At a grafting density regime where the theory propo ses the existence of a homogeneous layer, the formation of island stru ctures of grafted polymer with a size substantially higher than expect ed by the theory has been observed. Overshot polymer structures of lar ge sizes are created. The amount of grafted polymer is substantially h igher than that predicted from the conception of monolayer covering. T he grafting layer becomes impermeable for water only at a high amount of grafted polymer, which corresponds to the multilayer structure of t he coating. We suggested a mechanism for the grafting process that inc luded at least three stages: (a) first, a brushlike polymer layer is f ormed; (b) subsequently, a second layer of ungrafted chains is created in the regime when excess chains are forced out from the first layer; (c) big polymer clusters, with an average size of 100-200 nm due to g el polymerization in the clusters, formed in the force out regime.