Plastics are becoming more and more important and are an indispensable part of modern life. Scientists are thus interested in clearing up the details of polymerization processes, in which individual molecular building blocks are linked into long polymer chains or three-dimensional networks.
A Belgian and German team from the University of Leuwen and the Max Planck Institute for Polymer Research in Mainz has now been able to follow polymerizations from the point of view of individual molecules. As they report in the journal Angewandte Chemie, Johan Hofkens and his team used the techniques of fluorescence correlation spectroscopy and far-field microscopy to observe fluorescing sample molecules throughout the entire process of the radical polymerization of styrene.
Previous methods applied to this problem provided interesting insights into the reaction pathways of polymerizations; however, most are not capable of monitoring the entire reaction process. In addition, they only provide a picture of the reaction that is averaged over all of the molecules. Irregularities that occur during the polymerization cannot be recorded at the molecular level, although such heterogeneities have a large influence on the properties of the final polymer. Knowledge of such details can help to make polymerization processes easier to control and to improve the properties of the products.
Single-molecule spectroscopy does not average out differences between individual molecules; instead it highlights them. The researchers followed the polymerization by using fluorescing probes. During the reaction, which converts a solution of monomers into an ever-denser polymer matrix, the freedom of movement of the probe molecules is constantly decreasing. Fluorescence correlation spectroscopy makes it possible to measure the time during which individual probe molecules stay within a tiny defined space. This then enables the registration of the rapid molecular motions occurring in the barely reacted solution. Far-field microscopy directly displays the positions of the fluorescing probes and is well suited for following slow and immobilized molecules. The two methods are complementary and together they provide a picture of the translational motions throughout the entire polymerization process. Additional information is provided by probe molecules built in to the growing polymer.
Author: Johan Hofkens, Katholieke Universiteit Leuven, Heverlee (Belgium), http://www.chem.kuleuven.be/research/mds/index.htm
Title: Radical Polymerization Tracked by Single Molecule Spectroscopy
Angewandte Chemie International Edition, doi: 10.1002/anie.200704196
Johan Hofkens | Angewandte Chemie
WPI team grows heart tissue on spinach leaves
23.03.2017 | Worcester Polytechnic Institute
Inactivate vaccines faster and more effectively using electron beams
23.03.2017 | Fraunhofer-Institut für Organische Elektronik, Elektronenstrahl- und Plasmatechnik FEP
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
23.03.2017 | Power and Electrical Engineering
23.03.2017 | Earth Sciences
23.03.2017 | Life Sciences