Fabrication of polymer micro- and nanotubes with use of self-scrolling effect of strained thin polymer bilayer films.

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Recently we have developed a novel method of producing polymer tubes of mesoscopic diameter and high aspect ratio with use of self-scrolling of strained polymer bilayer films. The strain in the film arises due to different swelling of the polymers, composing the top and the bottom parts of the bilayer, in a selective solvent. Tubular structures are formed upon controlled release of the film from the substrate. We have fabricated by this technique the polystyrene-polyvinylpyridine tubes with the diameters ranging from 200 nm to 5 microns and aspect ratios up to several hundreds. The major advantage of the approach is the possibility of complex functionalization of the inner tube surface. Before the scrolling, the polymer film can be exposed to highly developed planar methods of surface functionalization (micro-contact printing, photolithography). This allows in principle to create non-trivial 3-D arrangement of patterns inside the tubes, such as helices, rings, etc. The tubes with complex functionalized inner surface can be useful for template-assisted self-assembly of colloidal particles and macromolecules, specific steric interaction of proteins and other biomolecules with the tube walls, etc. Interesting physical devices, such as nanosolenoids, can be produced by selective metallisation of the patterned internal surface of the tubes. Within the project, we pursue two major goals. First, we plan to optimize the technique of nanotube fabrication in order to minimize the diameter of the tubes. The thickness of the strained polymer bilayer will be reduced by the use of block-copolymers, which form layered structure on selective substrates. In this way we hope to produce the tubes with diameter as small as few dozens of nanometers. We intend also to fabricate the tubes of varying diameter ranging from sub-micron to sub-millimeter scale. These tubes could be useful for input-output connection of mesoscopic operational parts of the nanodevices and the macroscopic environment (supplies of reagents, etc.). Second, we plan to fabricate the tubes with simple non-trivial patterning of the internal surface by combining the micro-contact printing and photolithography with the self-scrolling effect.