Washington, June 4 : Researchers from University of Konstanz have developed a new method to produce an ultrathin polymer film, which could potentially be of great use for scientists and engineers.
The team led by Stefan Mecking at the University of Konstanz has now developed a new method to produce wafer-thin layers.
They made their films from individual prefabricated nanocrystal building blocks
The conventional method used for production of ultrathin polymer films (films with a thickness of less than 0.1 µm) begins with a dilute solution of the polymer in an organic solvent, which is applied to a surface.
In order to break up the crystalline structure of the solid polymer to get it into solution in the first place, high temperatures are usually required. The ordered crystalline layer only forms once the solvent is removed or cooled.
In the new method, the researchers used polyethylene (PE), a polymer with a simple chemical structure and a broad spectrum of technical applications ranging from films and packaging materials to technical components or implants.
PE is physiologically harmless and environmentally friendly-but has been hard to produce in ultrathin films.
The catalytic polymerization of ethylene with nickel complexes produces aqueous dispersions of crystalline polymer particles.
These are individual, separate single crystals consisting of crystalline lamella of about 25x6 nm surrounded by an amorphous (noncrystalline) layer with a thickness of 1 nm.
Amorphous domains on the surface are a typical occurrence in polymer crystals. Droplets of this aqueous dispersion are applied to a glass slide and spun at 2000 revolutions per minute (spin coating).
Excess liquid is spun away, leaving behind a wafer-thin uniform film with a thickness of 50 nm.
Although the amorphous domains only comprise a tiny portion of the volume of the particles, they interact very strongly with each other, holding the individual particles solidly in the film.
The study appears in in the journal Angewandte Chemie, the scientists made their films from individual prefabricated nanocrystal building blocks.