Dewetting of thin films

Depending on its actual thickness C, a thin film on a substrate can be stable, metastable, or linearly unstable. The stability of a 

Spinodal dewetting has been studied mostly for the case of the negligible slip. But the dewetting behavior with a weak slip (with 

Apart from the mobility M( ) 0 the dispersion relations in the no-slip or weak-slip (M( ) = /3 - - bt with the slip length b) and in the intermediate-slip regime (M( ) = bl ) are equal. For linearly unstable films with w ( ) 0, the dispersion relation has a maximum [ u ( )] /(4criv) at k = Q = ctiv), and it 

Concerning the theoretical description, thermal fluctuations have been taken into account on the level of the thin-film equation for the case of a negligible slip. 476,i8i vyitjjjjj jje validity of linear perturbation theory, the resulting power spectrum 5(k, t) of the thickness fluctuations of the film is given by S k, t) = 5/(k, t) 2) 

Beyond the linear regime, thin-film equations can be solved only numerically. But in particular the vanishing of the mobility factor 

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The bilayer morphology of thin asymmetric films of may be unstable. A regularly corrugated surface structure of the films was ascribed to spinodal transition into a laterally phase separated structure, where the surface morphology depended on the polymer incompatibility and the interfacial interactions [347, 348]. Recently, the phase separation and dewetting of thin films of a weakly incompatible blend of deuterated PS and poly(p-methylstyrene) have been monitored by SFM [349, 350]. Starting from a bilayer structure, after 454 h at T= 154 °C the film came to the final dewetting state where mesoscopic drops of... 

Kargupta, K., Sharma, A. Dewetting of thin films on periodic physically and chemically patterned surfaces. Langmuir 18(5), 1893-1903 (2002)... 

Sharma, A., Reiter, G. Morphological phase transititnis in sptmtaneous dewetting of thin films on homogeneous and heterogeneous surfaces. Phase Transit. 75(4—5), 377-399 (2002)... 

Spreading of droplets and dewetting of thin films are the two paradigmatic cases of dynamical wetting phenomena on homogeneous surfaces. 

M. Rauscher, R. Blossey, A. Miinch, and B. Wagner, Spinodal dewetting of thin films with large interfacial slip implications from the dispersion relation, Langmuir, 24,12290-12294 (2008). 

A. Ghatak, R. Khanna, and A. Sharma, Dynamics and morphology of holes in dewetting of thin films, / Colloid Interface Sci., 212, 483-494 [1999/... 

Sharma A, Mittal J, Verma R. Instability and dewetting of thin films induced by density variations. Langmuir 2002 18 10213-20. 

The speed of wetting has been measured by running a tape of material that is wetted either downward through the liquid-air interface, or upward through the interface. For a polyester tape and a glycerol-water mixture, a wetting speed of about 20 cm/sec and a dewetting speed of about 0.6 cm/sec has been reported [37]. Conversely, the time of rupture of thin films can be important (see Ref. 38). 

A. Milchev, K. Binder. Dewetting of thin polymer films adsorbed on solid substrates A Monte Carlo simulation of the early stages. J Chem Phys 705 1978-1989, 1997. 

G. Reiter. Dewetting of thin polymer films. Phys Rev Lett 62 75-78, 1992. 

G. Henn, D. J. Bucknall, M. Stamm, P. Vanhoorne, R. Jerome. Chain end effects and dewetting of thin polymer films. Macromolecules 29 4305 313, 1996. 

Stange, T. G., Evans, D. F. and Hendrickson, W. A. (1997) Nucleation and growth of defects leading to dewetting of thin polymer films. Langmuir, 13, 4459-4465. 

Seminal work has been performed by Brochard-Wyart and colleagues [110-113, 144, 145] on dewetting of thin polymer films with thicknesses smaller than the slip length b (high-slip regime). Assuming a Newtonian fluid, they have determined a characteristic length Aq = (ho b) = which is related to the transition... 

Mliller-Buschbaum, P., Gutmann, J.S., Stamm, M. Influence of blend composition on phase separation and dewetting of thin polymer blend films. Macromolecules 33(13), 4886-4895 (2000)... 

Muller-Buschbaum, P., Bauer, E., Wimnicke, O., Stamm, M. The control of thin film morphology by the interplay of dewetting, phase separation and microphase separation. J. Phys. Condensed Matter 17(9), S363-S386 (2005)... 

In conclusion, it seems that improvement of fluorocarbon performance may be possible by verifying which monomers could be useful and effective for the control or, indeed, the elimination of dewetting for thin films of FC polymers. 

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