Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Brushes in 3D

12.06.2013
Complex three-dimensional polymer brush nanostructures from photopolymerization

Polymer brushes are polymers in which individual polymer chains stand side by side on a surface, causing the chains to stick out like bristles on a brush.



In the journal Angewandte Chemie, American scientists have now presented a new simple method for making three-dimensional nanostructures in a controlled fashion from polymer brushes.

There are a wide variety of current and future applications for polymer brushes. For example, a coating of polymer brushes on a plastic surface such as an artificial heart valve or a dialysis machine can hinder the adsorption of proteins onto the surface. It can also be used in the fabrication of next-generation microelectronic devices. Other areas of application include biocompatible coatings for implants, chemical sensors, and new “intelligent” materials.

Although progress has been made with regard to new brush structures, current methods do not offer sufficient temporal and spatial control over the growth process. Usually, a self-organized monolayer of an initiator is assembled on a substrate and the polymer chains can grow out from there.

In order to obtain specific patterns, the initiator must be applied to the substrate in a corresponding pattern—a complex undertaking that is not manufacturable and does not allow for the generation of complex three-dimensional structures.

Craig J. Hawker and a team from the University of California, Santa Barbara, and The Dow Chemical Company (Midland, Michigan) have developed a new method that allows for the formation of brushes on a uniform initiator layer with both spatial and temporal control. Their simple method is based on a light-activated radical polymerization. The length of the bristles at any given location depends only on the duration and intensity of the local irradiation.

To form a specific structure, conventional photomasks can be used. These have openings in the areas to be irradiated and shield the other areas from the light. This allows for the formation of extensive patterns with submicrometer resolution in one step. All of this is made possible by a special iridium-based photocatalyst. It remains active for only a very short time after irradiation, so it cannot travel very far into nonirradiated areas while in its active state. It is even possible to use a grayscale photomask with continuously increasing opacity to produce gradated patterns.

Another advantage of this new method is that newly incorporated monomers are always added to the chain adjacent to the initiator, meaning that the initiator remains at the forward end of the growing chain. Because it is not destroyed as in other methods, and remains available at the right position, the polymerization can be stopped and restarted at any time. In this way the mask being used can be exchanged as often as desired. It is even possible to vary the monomer being used during the process. The complexity of accessible structures and applications is thus almost unlimited.

About the Author
Dr. Craig Hawker is the Alan and Ruth Heeger Professor of Interdisciplinary Studies at UCSB, and Director of the Dow Materials Institute and the California Nanosystems Institute. He is well known in the field of polymeric materials and has been honored with election as a Fellow of the Royal Society and the 2013 ACS Award in Polymer Chemistry.
Author: Craig J. Hawker, University of Califormia, Santa Barbara (USA), http://hawkergroup.mrl.ucsb.edu/craig-j-hawker
Title: Fabrication of Complex Three-Dimensional Polymer Brush Nanostructures through Light-Mediated Living Radical Polymerization

Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201301845

Craig J. Hawker | Angewandte Chemie
Further information:
http://pressroom.angewandte.org

More articles from Life Sciences:

nachricht If Machines Could Smell ...
19.07.2019 | Fraunhofer-Institut für Produktionstechnik und Automatisierung IPA

nachricht Algae-killing viruses spur nutrient recycling in oceans
18.07.2019 | Rutgers University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Better thermal conductivity by adjusting the arrangement of atoms

Adjusting the thermal conductivity of materials is one of the challenges nanoscience is currently facing. Together with colleagues from the Netherlands and Spain, researchers from the University of Basel have shown that the atomic vibrations that determine heat generation in nanowires can be controlled through the arrangement of atoms alone. The scientists will publish the results shortly in the journal Nano Letters.

In the electronics and computer industry, components are becoming ever smaller and more powerful. However, there are problems with the heat generation. It is...

Im Focus: First-ever visualizations of electrical gating effects on electronic structure

Scientists have visualised the electronic structure in a microelectronic device for the first time, opening up opportunities for finely-tuned high performance electronic devices.

Physicists from the University of Warwick and the University of Washington have developed a technique to measure the energy and momentum of electrons in...

Im Focus: Megakaryocytes act as „bouncers“ restraining cell migration in the bone marrow

Scientists at the University Würzburg and University Hospital of Würzburg found that megakaryocytes act as “bouncers” and thus modulate bone marrow niche properties and cell migration dynamics. The study was published in July in the Journal “Haematologica”.

Hematopoiesis is the process of forming blood cells, which occurs predominantly in the bone marrow. The bone marrow produces all types of blood cells: red...

Im Focus: Artificial neural network resolves puzzles from condensed matter physics: Which is the perfect quantum theory?

For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.

Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...

Im Focus: Extremely hard yet metallically conductive: Bayreuth researchers develop novel material with high-tech prospects

An international research group led by scientists from the University of Bayreuth has produced a previously unknown material: Rhenium nitride pernitride. Thanks to combining properties that were previously considered incompatible, it looks set to become highly attractive for technological applications. Indeed, it is a super-hard metallic conductor that can withstand extremely high pressures like a diamond. A process now developed in Bayreuth opens up the possibility of producing rhenium nitride pernitride and other technologically interesting materials in sufficiently large quantity for their properties characterisation. The new findings are presented in "Nature Communications".

The possibility of finding a compound that was metallically conductive, super-hard, and ultra-incompressible was long considered unlikely in science. It was...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on UV LED Technologies & Applications – ICULTA 2020 | Call for Abstracts

24.06.2019 | Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

 
Latest News

Heat flow through single molecules detected

19.07.2019 | Physics and Astronomy

Heat transport through single molecules

19.07.2019 | Physics and Astronomy

Welcome Committee for Comets

19.07.2019 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>