Copolymers surface segregation

Fig. 3. ESCA results on the surface segregation of the Polycarbonate homopolymer/Poly-carbonate-Polydimethylsiloxane segmented copolymer blends 1S0)...

Two different types of behavior characterize the temperature dependence of surface segregation in blends composed of the olefinic copolymers. Larger surface energy difference Afs between blend components (say at TreX) results in complete wetting behavior observed even far below the critical point Tc. On the other hand, a small difference in Afs (at the same Tref) makes the wetting transition possible, in principle, at temperatures close to Tc. 

Surface segregation Surface/interfacial energy Layered segregation Nanometer Block copolymer segregation from blends afford nano-structured interfaces [4, 142, 143]... 

Nanostructured Interfaces by Surface Segregation of Block Copolymers... 

In this chapter, we aim to provide an overview of the possibilities of using surface segregation not only to functionaUze and but also to nanostructure polymer surfaces. For this purpose, we first discuss the factors that may favor or reduce the presence of a particular additive at the interface. As depicted here, the molecular structure, the functional groups contained within the polymer, and other factors such as hydrophilicity of the environment or the temperature will play a key role on the migration of an additive towards the surface. More interestingly, the use of block copolymers within the blends permits the formation, by self-assembly, of different structures at the nanometer scale, thus providing an interesting way to fabricate different nanometer scale structures at the interface. 

Studies concerning functional surfaces produced by surface segregation of copolymers typically involved the use of either double hydrophobic copolymers [121, 122] or amphiphilic block copolymers [123-126] as additives to be placed at the surface. These copolymers are designed to contain hydrophobic segments... 

A crucial aspect on polymer blends containing block copolymers concerns the concentration of block copolymer both in bulk and at the surface. The former can be controlled in the design of the initial blend and the latter depends not only on the amount initially introduced in the blend but also on the eventual surface segregation. In Fig. 5.18 is schematically illustrated the block copolymer arrangement of binary blends with variable amount of block copolymer. At low concentrations (a, b) the block copolymer can reside either in the bulk or at the interface and the amount of block copolymer segregated at the interface is directly related to the... 

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