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
Researchers find new mutation in the leptin gene
24.06.2019 | Texas Biomedical Research Institute
Straight to the heart
24.06.2019 | Max-Delbrück-Centrum für Molekulare Medizin in der Helmholtz-Gemeinschaft
From June 25th to 27th 2019, the Fraunhofer Institute for Digital Media Technology IDMT in Ilmenau (Germany) will be presenting a new solution for acoustic quality inspection allowing contact-free, non-destructive testing of manufactured parts and components. The method which has reached Technology Readiness Level 6 already, is currently being successfully tested in practical use together with a number of industrial partners.
Reducing machine downtime, manufacturing defects, and excessive scrap
The quality of additively manufactured components depends not only on the manufacturing process, but also on the inline process control. The process control ensures a reliable coating process because it detects deviations from the target geometry immediately. At LASER World of PHOTONICS 2019, the Fraunhofer Institute for Laser Technology ILT will be demonstrating how well bi-directional sensor technology can already be used for Laser Material Deposition (LMD) in combination with commercial optics at booth A2.431.
Fraunhofer ILT has been developing optical sensor technology specifically for production measurement technology for around 10 years. In particular, its »bd-1«...
The well-known representation of chemical elements is just one example of how objects can be arranged and classified
The periodic table of elements that most chemistry books depict is only one special case. This tabular overview of the chemical elements, which goes back to...
Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.
Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...
Researchers at TU Graz calculate the most accurate gravity field determination of the Earth using 1.16 billion satellite measurements. This yields valuable knowledge for climate research.
The Earth’s gravity fluctuates from place to place. Geodesists use this phenomenon to observe geodynamic and climatological processes. Using...
29.04.2019 | Event News
17.04.2019 | Event News
15.04.2019 | Event News
24.06.2019 | Agricultural and Forestry Science
24.06.2019 | Life Sciences
24.06.2019 | Medical Engineering