Polymerization From the Individual Molecule's Point of View

Dec 18, 2007

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.

Citation: Johan Hofkens, Radical Polymerization Tracked by Single Molecule Spectroscopy, Angewandte Chemie International Edition, doi: 10.1002/anie.200704196

Source: Angewandte Chemie

Explore further: A greener source of polyester—cork trees

add to favorites email to friend print save as pdf

Related Stories

High-strengh materials created under pressure

Mar 18, 2014

At Vienna University of Technology, materials for lightweight construction, protective clothing or sports equipment can be produced at high temperatures and high pressures. This process is faster, better ...

Recommended for you

A greener source of polyester—cork trees

10 hours ago

On the scale of earth-friendly materials, you'd be hard pressed to find two that are farther apart than polyester (not at all) and cork (very). In an unexpected twist, however, scientists are figuring out ...

Breakthrough points to new drugs from nature

12 hours ago

Researchers at Griffith University's Eskitis Institute have developed a new technique for discovering natural compounds which could form the basis of novel therapeutic drugs.

World's first successful visualisation of key coenzyme

12 hours ago

Japanese researchers have successfully developed the world's first imaging method for visualising the behaviour of nicotine-adenine dinucleotide derivative (NAD(P)H), a key coenzyme, inside cells. This feat ...

User comments : 0

More news stories

Breakthrough points to new drugs from nature

Researchers at Griffith University's Eskitis Institute have developed a new technique for discovering natural compounds which could form the basis of novel therapeutic drugs.

A greener source of polyester—cork trees

On the scale of earth-friendly materials, you'd be hard pressed to find two that are farther apart than polyester (not at all) and cork (very). In an unexpected twist, however, scientists are figuring out ...