Polymer Tubes by Rolling of Polymer Bilayers
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1272-OO01-09
Polymer Tubes by Rolling of Polymer Bilayers Kamlesh Kumar1,2, Bhanu Nandan1, Valeriy Luchnikov3, Svetlana Zakharchenko1, Leonid Ionov1Manfred Stamm1 1
2
Leibniz Institute of Polymer Research Dresden Hohe Str 6, 01069 Dresden
present address: Oregon Health & Science University 3181 SW Sam Jackson Park Rd. Portland, USA
3
Institut de Science des Materiaux de Mulhouse, LRC 7228 CNRS & Universite de Haute Alsace, 15, rue Jean Starcky, Mulhouse 68057, France
ABSTRACT Polymer micro- and nanotubes are of growing interest for design of microfluidic devices, chromatography, biotechnology, medicine chemical sensors, etc. One approach for the design of tubes is based on use of self-rolling thin films. Here we overview our recent progress in the fabrication polymeric self-rolling tube. INTRODUCTION Polymer micro- and nanotubes have been demonstrated to possess remarkable applications in various fields such as microfluidic devices 1 , chromatography, biotechnology 2, medicine 3-4 and chemical sensors 5. Among different methods for preparation of tubes, stress-induced self-rolling of thin films deserved a particular interest. This method was originally developed for design of inorganic (metal and metal oxide) tubes 6-7. Recently, we applied this approach for fabrication of polymeric tubes. This paper overviews our recent developments in this field. DESIGN OF SELF-ROLLING TUBES Our approach is based on use of thin polymeric bilayers deposited on a substrate8-9. The rolling of tube is provided by the bending moment due to swelling properties of chemically dissimilar polymers in selective solvents (Figure 1). The lateral force, which creates the bending moment, arises in response to an unequal change in the specific volume of the components of the film. This principle was used for fabrication of polystyrene (PS)/poly (4-vinyl pyridine) (P4VP) film. The polymer bilayer was produced by consecutive deposition of PS and P4VP, from toluene and chloroform solutions, respectively. The tube formation proceeds from an opening in the film made by photolithography or by mechanical scratching followed by immersion of patterned sample in dodecylbenzene sulfonic acid (DBSA) solution or in acidic aqueous environment. DBSA forms supramolecular complexes with pyridine rings of P4VP and increases the specific volume of the polymer. Since the solution is neutral to PS layer, bilayer film develops strain due to unequal swelling of polymers in solution of DBSA and hence the film bends and scrolls in order to minimize its free energy and form tubes. Using layers with two-dimensional gradient of
thickness 10, we thoroughly investigated process on tube formation with respect to acidity of the solution and UV dose. It was found that rate of rolling increased with the acidity of the solution. Tube diameter and rate of rolling decreased with the increase of the UV exposure time. Moreover, increase of thickness of PS results in increase of the diameter of tube.
Figure 1. Scheme of fabrication of polymeric microtubes with using polymeric
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