Interfacial mixing

Fig. 10. X-ray reflectivity curves of polystyrene (PS)/poly-p-bromostyrene (PBrS) on a glass substrate before (solid line) and after annealing for 13 h at 130 °C (dashed tine) [191]. The width of the interface changes from 1.3 nm to 2.0 nm due to interfacial mixing of components. The X-ray wavelength is 0.154 nm and films have a thickness of 37.8 nm (PS) and 45.0 nm (PBrS), respectively...

This area of research is still at its beginning and many aspects are not resolved. This includes in particular the structure and conformation of polymers at an interface as well as the modification of polymer dynamics by the interface. We have given several examples of the potential of surface and interface analytical techniques. They provide information on surface roughness, surface composition, lateral structure, depth profiles, surface-induced order and interfacial mixing of polymers on a molecular and sometimes subnanometer scale. They thus offer a large variety of possible surface and interface studies which will help in the understanding of polymer structure and dynamics as it is modified by the influence... 

With respect to the sharpness of the top metal/molecule interface, thermodynamically, given the vastly different lattice energies of the soft-condensed matter SAM and the hard metal layer, one would expect the interface to be near the limit of no interfacial mixing (essentially a large chi mixing parameter, x l) the interface to approach an infinitely sharp condition. An example of the complexity that can be introduced in this simple picture is illustrated by considering the case of... 

For a solution-processed active interface, in which either the gate dielectric material is deposited from solution on to a solution-processible semiconducting material or vice versa, it is critical to avoid dissolution or swelling effects during deposition of the upper layer, which can lead to interfacial mixing and increased interface roughness. The preferred approach to achieve this is to choose orthogonal solvents for the deposition of the multilayer structure [23]. 

Wang Y, Chen X, Hamers RJ (1994) Atomic-resolution study of overlayer formation and interfacial mixing in the interaction of phosphorus with Si(001), Phys. Rev. B 50 4534 1547... 

Bis(hydroxymethyl) furan and 5-hydroxymethyl furfural (available from C6 sugars) have been oxidized to furan-2,5-dicarboxylic acid (44)- Linear polyesters, polyurethanes, and polyamides containing these monomers have been described in the literature (45-43) and have been made via condensation polymerization techniques including bulk, solution, and interfacial mixing procedures. Gandini (5,34) reviewed the poly condensation reactions up to 1986 and... 

Monte Carlo and molecular dynamics calculations of the density profile of model system of benzene-water [70], 1,2-dichloroethane-water [71], and decane-water [72] interfaces show that the thickness of the transition region at the interface is molecu-larly sharp, typically within 0.5 nm, rather than diffuse (Fig. 4). A similar sharp density profile has been reported also at several liquid-vapor interfaces [73, 74]. The sharpness of interfaces thus seems to be a general characteristic of the boundary between two stable phases and it is likely that the presence of supporting electrolytes would not significantly alter the thickness of the transition region at an ITIES. The interfacial mixed solvent layer [54, 55], if any, would probably have a thickness comparable with this thin inner layer. 

An isolation layer can be incorporated between the two layers to alleviate the interfacial mixing problem. Table 3.9 summarizes such three-layer PCM systems composed of a diazoquinone resist, an isolation layer, and PMMA. The use of aluminum, amorphous silicon, and a spin-on antireflective coating... 

Adedeji A, Hudson SD, Jamieson AM. Effect of exothermic interfacial mixing on interfacial activity of a block copolymer. Macromolecules 1996 29 2449— 2456. 

Application of a protective overcoat to seal off airborne contaminants was also a popular approach initially. Although many polymers, lipophilic and hydrophilic, have been evaluated as a topcoat, water-soluble poly[ (meth)acryhc acid] is most commonly employed, which can be cast from a water solution without interfacial mixing with the resist layer and can be removed during aqueous base development. However, it has been reported that a poly(acrylic acid) overcoat allows diffusion of water, which reportedly contaminates a chemical amplification resist [211]. Poly(cx-methylstyrene) has been recommended as a good barrier against both airborne base and water [211]. 

Resistant to common casting solvents with no interfacial mixing with the top resist layer... 

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