China Shanghai Yixin Chemical Co., Ltd. Company News

     A typical Belousov-Zhabotinsky pattern of concentric circles, observed in this case in   polymer-controlled crystallisation and self-organisation from barium carbonate. The   structures are similar to a computer-simulated pattern (smaller circle, upper right). The   block copolymer used appears in the picture as a shortened molecule structure.          In order to survive, biological systems need to form patterns and organise   themselves. Scientists at the Max Planck Institute for Colloids and Interfaces in   Potsdam, Germany, have now combined self-organisation with chemical pattern   formation.They coupled an oscillating chemical reaction with polymer-controlled   crystallisation and self-organisation in barium carbonate. In this way, they proved that   oscillating reactions - like the renowned Belousov-Zhabotinsky reaction - can also take   place in multi-phase systems.     On basis of these results, scientists can better explain chemical reactions which are   out of thermodynamic balance, as well as biological pattern formation in nature.   Furthermore, these results could lead to the creation of surfaces with new kinds of   structures (Angewandte Chemie, June 21, 2006).   Scientists are especially interested in oscillating chemical reactions. These occur when   reaction products periodically and repeatedly change. Their behaviour is of importance   to many fields of study - including chaos research. That is because these reaction   systems are always complex and far away from thermodynamic equilibrium. One   particularly well-known example is the "Belousov-Zhabotinsky" reaction. In it, a   coloured indicator is used to make the reaction products of a coupled redox reaction   visible. They typically take on the pattern of concentric circles, spreading out, for   example, across a petri dish.      Mathematically, spatially oscillating reactions can be described as "reaction-diffusion   systems". This means that it is not just chemical reactions which influence the amount   of material at a certain point in space. Diffusion also plays a role - the exchange of   material with the surrounding area. In such simulations, we get the typical concentric   circle pattern of a Belousov-Zhabotinsky reaction. In the picture above, it is indicated in   red-violet.      Researchers from Potsdam have now proven that these oscillating reactions can   also apply to multi-phase systems, and even to the self-organisation processes of   nanoparticles. What is central is that in a multi-phase reaction system, it is possible to   formulate either an autocatalyic or autoinhibiting reaction step. This leads an oscillating   system to be constructed, and ultimately a pattern to be formed.       The researchers used a newly synthesized polymer to create the typical concentric   circle pattern, via controlled barium carbonate crystallisation (see image). Such   patterns correspond quite well to the calculations in a simulation. The researchers also   were able to formulate a complex coupled reaction system including crystallisation,   complexation, and precipitation reactions and identify the autocatalytic formation of a   complex between barium and the polymer.       Notably, the elongated crystalline structures which made up the circular pattern are   themselves created by superstructures of nanoparticles, which are themselves created   by self-organisation (see image). In this way, Max Planck researchers have shown for   the first time that the Belousov-Zhabotinsky reaction does not just take place in a   solution, but also in multi-phase systems, and in nanoparticle self-organisation. This   discovery is not only important to research into reactions far away from thermodynamic   equilibrium. It can also help explain biological pattern formation. One example of   biological self-organisation is mussel shell patterns. They are created via controlled   crystallisation, just like the model systems of the researchers in Potsdam used.         Interestingly, these patterns also mathematically duplicate reaction-diffusion systems   exactly.