Interface Interfacial roughening

Figure 4.14. (a) An interface without capillary waves, with some intrinsic interface width wi. In (b) the interface is roughened by thermally excited capillary waves. A technique that averages over a distance L will measiue a larger apparent interfacial width w L). 

Similarly, Jiao also observed the interfacial roughening in a system consisting of polystyrene/benzyl amine end-capped polystyrene/styrene-maleic anhydride random copolymer. He proposed that a microemulsion was formed when the interfacial tension was driven negative by the graft copolymer formed at the interface [72]. 

Although the mechanisms of polyimide/metal adhesion remain to be fundamentally elucidated, it is generally accepted that the interfacial diffusion of metallic entities into the polyamic acid plays a key role at the interface [156-158]. Two main theories have been reported explaining the adhesion of the Pl/metal bond chemical and mechanical bonding [159]. Initial work emphasized mechanical bonding and most efforts were dedicated to the physical roughening of the substrate by different abrasive methods as well as chemical treatments in order to improve metal to polyimide adhesion by increasing the metal surface area [156,160-164]. 

Fig. 36. Schematic temperature variation of intcrfacial stiffness kn I K and interfacial free energy, for an interface oriented perpendicularly to a lattice direction of a square a) or simple cubic (b) lattice, respectively. While for tl — 2 the interface is rough for all non zero temperatures, in d — 3 il is rough only for temperatures T exceeding the roughening transition temperature 7r (see sect. 3.3). For T < 7U there exists a non-zero free energy tigT.v of surface steps, which vanishes at T = 7 r with an essential singularity. While k is infinite throughout the noil-rough phase, k Tic reaches a universal value as T - T . Note that k and fml to leading order in their critical behavior become identical as T - T. ...

Figure 7.3 Evolution of the interfaciai morphoiogy due to crowding of the interface by interfacial copolymers and consequent decrease ofthe interfaciai tension (a) interfaciai roughening (b) formation of pinch-offs and (c) formation of micro-emulsions on the continuous phase.

Bennema et al. [47] introduce a modeling concept for the prediction of crystal morphology grown in the presence of additives, which is based on the knowledge of the internal crystal structure. The method employs the theory of the roughening temperature [48]. Preliminary investigations on the solid-liquid interface revealed an intensive structuring of molecules in the interfacial fluid phase and none in the bulk fluid phase [49]. 

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