linked to by 1 published by Science on Sat 7th Jul 07 Austin M Evans, Lucas R Parent, Nathan C Flanders, Ryan P Bisbey, Edon Vitaku, Matthew S Kirschner, Richard D Schaller, Lin X Chen, Nathan C Gianneschi, William R Dichtel
Polymerization of monomers into periodic two-dimensional networks provides structurally precise, layered macromolecular sheets that exhibit desirable mechanical, optoelectronic, and molecular transport properties. Two-dimensional covalent organic frameworks (2D COFs) offer broad monomer scope but are generally isolated as powders comprising aggregated nanometer-scale crystallites. We found that 2D COF formation could be controlled using a two-step procedure in which monomers are added slowly to preformed nanoparticle seeds. The resulting 2D COFs are isolated as single-crystalline, micrometer-sized particles. Transient absorption spectroscopy of the dispersed COF nanoparticles revealed improvement in signal quality by two to three orders of magnitude relative to polycrystalline powder samples, and suggests exciton diffusion over longer length scales than those obtained through previous approaches. These findings should enable a broad exploration of synthetic 2D polymer structures and properties.
Let us pause to consider the weirdness of diamond. Not because diamonds are rare – they’re not, at least compared to many other minerals and gemstones. But diamond itself has very unusual physical properties, and that comes down to its structure....
Copyright for blog posts and author images rests with the authors.