Polystyrene films have been grafted by radical polymerization in situ on the surface of glass slides. The morphology of these films resulting from different grafting temperatures has been investigated by both the contact angle method and scanning probe microscopy with respect to the grafting time. At a grafting density regime where the theory proposes the existence of a homogeneous layer, the formation of island structures of grafted polymer with a size substantially higher than expected by the theory has been observed. Overshot polymer structures of large sizes are created. The amount of grafted polymer is substantially higher than that predicted from the conception of monolayer covering. The grafting layer becomes impermeable for water only at a high amount of grafted polymer, which corresponds to the multilayer structure of the coating. We suggested a mechanism for the grafting process that included at least three stages:  (a) first, a brushlike polymer layer is formed; (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 gel polymerization in the clusters, formed in the force out regime.

Kinetics of the grafting free radical polymerization of styrene from the surface of Si wafers with a top silica layer was studied by in situ ellipsometric measurements of the grafted amount (A). Wafers uncovered and covered by physisorbed azo- or peroxide macroinitiator or covalently bonded with the substrate azo-initiator were used. Additional initiator of the same chemical nature was added to the bath solution (bulk). It was found that the grafted amount approaches a plateau value depending on the rate of grafting polymerization. At low rates, the plateau A values are on the order of 1−2 mg/m2, whereas at high rates, they are typically 10−15 mg/m2. Two kinetic regimes were studied where (1) the surface-attached chains terminate by chain transfer to the bulk or (2) the grafted chains terminate with the bulk free radicals. The rate of polymerization for the both regimes is linearly proportional to the surface density of the initiator. Within regime 2, the rate of polymerization has inverse square root dependence on the concentration of the initiator in the bulk. Two models were applied to explain the kinetics, which provide good agreement with the experimental data.

Failure mechanisms in polymer composites were investigated with the method of ultra-small-angle X-ray scattering using synchrotron radiation and acoustic emission analysis simultaneously. The composites were prepared from polystyrene filled with glass beads with different coatings. The two-dimensional scattering patterns were analyzed by means of a cylinder model, while the curves of the acoustic emission signals per stress or amplitude interval were calculated and fitted by a Weibull distribution function.