Pattern formation induced by an electric field in a polymer-air-polymer thin film system
Royal Society of Chemistry (RSC)
Strong electric fields produce forces that can overcome the surface tension in thin liquid polymer films and in this way induce an instability of the free surface of the film, that triggers the formation of structures on a micrometer length scale. Here, we study experimentally a polymer-air-polymer system for several combinations of polymer films. These results are accompanied by theoretical considerations based on coupled long-wave time evolution equations for the two free surface profiles. The linear stability and nonlinear time evolution are investigated and compared to the experimental findings. The prediction that the instability always evolves through a mirror mode that couples the two surfaces in an anti-phase manner agrees well with the experimental results. The model describes well the linear (early stage) evolution of the instability. In the non-linear (later stage) evolution, topographical differences in the instability pattern occur if the mobilities of the two layers significantly differ and an unpredicted acceleration of growth is seen in thinner less mobile films. Possible reasons for the mismatch are discussed.
Polymers , Boundary layer flow , Electric fields , Polymer films , Stability , Surface tension , Free surfaces , Linear stability , Micrometer lengths , Pattern formation , Strong electric fields , Thin film systemsThin liquidsTime evolution equationsTime evolutions , Thin film systems , Thin liquids , Time evolution equations , Time evolutions
Amarandei, G., Beltrame, P., Clancy, I., O'Dwyer, C., Arshak, A., Steiner, U., Corcoran, D. and Thiele, U. (2012) 'Pattern formation induced by an electric field in a polymer-air-polymer thin film system', Soft Matter, 8(23), pp. 6333-6349. doi: 10.1039/C2SM25273B
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