Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fabrication method can affect the use of block copolymer thin films

04.05.2012
A new study by a team including scientists from the National Institute of Standards and Technology (NIST) indicates that thin polymer films can have different properties depending on the method by which they are made.

The results* suggest that deeper work is necessary to explore the best way of creating these films, which are used in applications ranging from high-tech mirrors to computer memory devices.


The method of creating a thin film can have great effect on the material, such as the orientation of the tiny cylinders in this film proposed for use in computer memory. One method of film creation is far more effective at creating copolymer films with cylinders that stand on end (b), as they must to be usable. Scale bar represents 200 nanometers. Credit: NIST

Thin films spread atop a surface have many applications in industry. Inexpensive organic solar cells might be made of such films, to name one potential use. Typically they're made by dissolving the polymer, and then spreading a small amount of the liquid out on a surface, called a substrate. The solution becomes a film as the solvent dries and the remainder solidifies. But as this happens, stresses develop within the film that can affect its structure.

Manufacturers would like to know more about how to control these stresses to ensure the film does what they want. But scientists who study film formation often use a different method of casting films than a manufacturer would. One method used in industry is "flow coating"—similar to spreading frosting across a cake. Another method is "spin casting"—placing a drop of liquid on a substrate that spins rapidly and spreads the droplet out evenly by centrifugal force. Both methods create smooth films generally, but the team decided to examine whether the two methods create different effects in finished films consisting of a self-assembling block copolymer.

"It's an important question because some proposed applications intend to take advantage of these effects," Douglas says.

The team's comparison led to results that surprised them. Although the rapid spinning of spin casting is very dynamic, suggesting it would convey more stress to the resulting film, it actually led to fewer residual stresses than flow coating did. As previous studies have shown that leftover solvent can lead to stresses in the film, the team's new theory is that because the solvent evaporates from the developing film more slowly in flow coating, this solvent discourages the film solids from arranging themselves into the equilibrium structure.

For one example, the practical benefits of this understanding could help manufacturers who propose making computer memory devices from thin films in which the solids arrange themselves as tiny cylinders in the film. Such devices would require the cylinders to stand on end, not lay down flat.

"We find we can get them to stand up much more easily with one casting method than another," Douglas says. "If we can get better results simply by varying the mode of film casting, we need to explore more deeply what happens when you make films by different methods."

* X. Zhang, J.F. Douglas and R.L. Jones. Influence of film casting method on block copolymer ordering in thin films. Soft Matter, Mar. 21, 2012. doi:10.1039/C2SM07308K.

Chad Boutin | EurekAlert!
Further information:
http://www.nist.gov

More articles from Process Engineering:

nachricht Quick, Precise, but not Cold
17.05.2017 | Fraunhofer-Institut für Lasertechnik ILT

nachricht A laser for divers
03.05.2017 | Laser Zentrum Hannover e.V.

All articles from Process Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

High conductive foils enabling large area lighting

29.06.2017 | Power and Electrical Engineering

Designed proteins to treat muscular dystrophy

29.06.2017 | Life Sciences

Climate Fluctuations & Non-equilibrium Statistical Mechanics: An Interdisciplinary Dialog

29.06.2017 | Seminars Workshops

VideoLinks
B2B-VideoLinks
More VideoLinks >>>