Synthesis and Behavior of the Polymer Covering on a Solid Surface. 3. Morphology and Mechanism of Formation of Grafted Polystyrene Layers on the Glass Surface

Abstract

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.

Effects of ozone in surface modification and thermal stability of SEBS block copolymers

“…The values of contact angles of the non-treated samples were lower than those reported for PS surface (90 ) [36] and for polyethyleneebutylene copolymer surface (99 ). This difference indicates that surfaces were definitively non uniform and to study the effect of roughness advancing and receding contact angles (q A and q R , respectively) were determined.…”

Effect of Molecular Structure on Friction and Wear of Polymer Thin Films Deposited on Si Surface

“…PE film has shown a water contact angle of 97°which is in the range reported for bulk polyethylene (91-99°) [24,25] and shows that PE film completely covers the SAM surface. PS film has shown a water contact angle of 80°which is marginally less than that reported for PS film (90°) [26]. Both PE and PS film surfaces are hydrophobic due to their hydrocarbon groups and also suggest the absence of anhydride groups on the surface.…”

Gradient Polymer Layers by “Grafting To” Approach

“…There are several major techniques available for the layer preparation including diffusion techniques, the density gradient method, hydrolysis and plasma/corona discharge. [8] End-grafted polymer layers are well known to dramatically affect the surface properties of substrates such as adhesion, [10,11] lubrication, [12] wettability, [13,14] friction, [15] and biocompatibility. [16] Recently, the gradient surfaces have been obtained by synthesis of end-grafted polymer layers on a substrate using gradient of concentration of surface tethered initiator of free radical polymerization in a ''grafting from'' procedure.…”