Interface Segregation Principle

The Interface-Segregation Principle Clients should not be forced to depend on methods that they do not use. 

Ternary blends One way to overcome these limitations is the use of ternary polymer blends. This approach makes use of the principle described in section 1.1.2, in which one of the polymer components wets the interface of the other two. By providing a pre-pattemed substrate with surface regions, to which these two polymer segregate, it is possible to form structures in the intercalated polymer with dimensions that are not directly connected to the substrate pattern. 

The experimental approach examines bilayers with a limited precision in depth z (8=a few nanometers) and in volume fraction < > (a few percent). It assumes that at least the central part of the analyzed profile ( >(z) describes only the internal interface between coexisting phases ([q and 2. This is not necessarily true when surface segregation regions, adjacent to both external interfaces, cannot be neglected as it is for very thin films. Related finite size effects are discussed in detail in Sect. 3.2 theoretical models and computer simulations expect that size effects modify the intrinsic profile internal interface. Therefore size effects may lead in principle to systematic errors [6] of binodal values determined for films which are very thin or are profiled at T—>TC (where the ratio D/w is also small due to the diverging w). 

Typically, the segregated phase has a smaller characteristic length scale than the continuous phase. In a monomer-flooded emulsion polymerization, the aqueous continuous phase will contain monomer drops and polymer particles, although large monomer drops may also contain smaller water droplets or polymer particles (if crosslinked or insoluble). This is the consequence of a thermodynamic principle that acts in the direction of a constant chemical potential for all species, throughout the whole system. In other words, there is a driving force that pushes all of the components of a system to be present in different proportions in all of its phases. This principle has been proven in spontaneous emulsification experiments, where droplet formation is observed on either side of the liquid-liquid interface [7]. Moreover, the chemical potential is size-dependent at the colloidal scale and hence, particles of different size will possess different compositions. 

Next we consider the effect of the block copolymer composition /= NfJN on the ordered morphology. In the limit of very strong segregation, that is, zero interface width, the natural idea is to let the stable ordered phase correspond to the phase with the minimal interface surface. To illustrate this principle and to obtain a semiquantitative estimate of the values of/for which the transitions between the three classical stmctures occur, we consider an LxLxL volume of the self-assembled diblock copolymer system. The ordered states that will be compared are the lamellar phase, a square lattice of cylinders, and spheres on a simple cubic (SC) lattice. L is the periodicity length scale of the layers, the square, and the cubic lattice (Figure 19). The LxLxL volirme element contains one cylinder resp. one sphere. Volirme conservation (Figure 20), therefore, requires fL = 7tRcL = 4n/SRs, where Rc and Rs are the radii of the cylinder and the sphere, respectively. 

A second type of irreversible phenomena commonly occurs at the interface itself. They may be irreversible chemical reactions of the sort deliberately produced in certain structural adhesive joints. In addition, in certain polymeric contacts, diffusion processes may produce either the segregation of low molecular weight species at the interface or diffusion bonding by the intermixing of the polymeric chains. The former will reduce adhesion and the latter will increase it. In principle, for both processes the time dependent value of the adhesion may be used to monitor the extent of the diffusion processes" " " and hence provide an estimate of the diffusion coefficient. For these and other reasons it is often found that the adhesion is a strong function of the temperature and contact time. 

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