Saturday, 8 December 2012

Filters using Self-assembling Supramolecular Nanofiber Webs

Hans-Werner Schmidt of the University of Bayreuth, Macromolecular Chemistry, Bayreuth, (Germany) described the creation of nanofibres from complex monomers designed to self-assemble by hydrogen bonding in one dimension only, the resulting polymers clustering together into bundles. Initially the bundle diameters would be 10-20nm but these too would aggregate into larger bundles up to a micron in diameter.

The 1-3-5 trisamide derivative of benzene could be dissolved in 2-butanone at 0.4% and would self-assemble into nanofibres on cooling from 240C. This could be applied to the surface of a nonwoven to form a filter (2.8% nanofibres concentrated at the surface.) An example with 1% derivative in 2-butanone giving 7.6% nanofibre on nonwoven was shown to give an impressive network on the surface, the pore size of which depended on the solution temperature over a 25-120C range. Here the nanofibres formed in the pores of the nonwoven surface.

Asked about the temperature sensitivity of the nanofibres, Mr Schmidt said he had shown lower melting point products, but others were stable up to 350C. He was working on a water-based solution to replace the 2-butanone.

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