Designer Gradients Speed Surface Science Experiments

Jun 08, 2006
Designer Gradients Speed Surface Science Experiments

Researchers from the National Institute of Standards and Technology have demonstrated an elegantly simple technique for synthesizing a wide variety of complex surfaces that vary in a controlled fashion across a test strip. The new technique is so flexible that it can be applied to surface science experiments ranging from developing better paints to exploring the bonding of proteins to cell membranes.

So-called “gradient composition surfaces”—their chemical composition changes gradually across the surface—have been shown to be powerful research tools for rapid, high-throughput testing of complicated surface properties, but they can be tricky to build. The new NIST technique described in a recent paper in Advanced Materials coats a silicon wafer with a brush-like copolymer surface, varying the relative concentration of two components, or monomers, of the polymer along the length of the substrate. The dense polymer brush provides a controlled interaction surface at the top while effectively masking the underlying substrate.

The heart of the NIST technique is a combined microfluidic mixer and reaction chamber. The two components are injected into the mixer with gradually changing flow rates and mix thoroughly before filling a thin reaction chamber holding the silicon wafer substrate. Once the solution leaves the mixing region, the narrow dimensions of the reaction chamber inhibit further mixing, so the varying composition ratios through the chamber remain stable while the solution polymerizes on the substrate.

Because it keeps the fluid mixture concentrations stable for long periods, the new technique is unique in its ability to accommodate a wide variety of materials, potentially producing test surfaces for studying surface phenomena ranging from nanoscale interactions of biomolecules—critical for improving the performance of tissue-engineered medical products or for identifying the fundamental mechanisms key to cell/surface adhesion—to the performance of new products like paints or adhesives. The specific polymer used in these proof-of-concept experiments, for example, is typical of a temperature- or acidity-sensitive polymer that might be used in a drug delivery system.

Citation: C. Xu, S.E. Barnes, T. Wu, D.A. Fischer, D.M. DeLongchamp, J.D. Batteas, and K.L. Beers. Solution and surface composition gradients via microfluidics confinement: fabrication of a statistical-copolymer-brush composition gradient. Adv. Mater. 2006, 18, 1427-1430.

Source: NIST

Explore further: Global scientific team 'visualizes' a new crystallization process (w/ video)

add to favorites email to friend print save as pdf

Related Stories

Meteorites yield clues to Martian early atmosphere

4 hours ago

(Phys.org) —Geologists who analyzed 40 meteorites that fell to Earth from Mars unlocked secrets of the Martian atmosphere hidden in the chemical signatures of these ancient rocks. Their study, published ...

New light on novel additive manufacturing approach

Apr 11, 2014

(Phys.org) —For nearly a century, electrophoretic deposition (EPD) has been used as a method of coating material by depositing particles of various substances onto the surfaces of various manufactured items. ...

Sustainable ways to keep us flying

Apr 09, 2014

The global aviation industry continues to expand, with over 3 billion people expected to fly commercially in 2014, along with 38 million metric tons of cargo. This activity will have a huge impact on the ...

Recommended for you

Novel technique opens door to better solar cells

Apr 14, 2014

A team of scientists, led by Assistant Professor Andrivo Rusydi from the Department of Physics at the National University of Singapore's (NUS) Faculty of Science, has successfully developed a technique to ...

Probing metal solidification nondestructively

Apr 14, 2014

(Phys.org) —Los Alamos researchers and collaborators have used nondestructive imaging techniques to study the solidification of metal alloy samples. The team used complementary methods of proton radiography ...

Glasses strong as steel: A fast way to find the best

Apr 13, 2014

Scientists at Yale University have devised a dramatically faster way of identifying and characterizing complex alloys known as bulk metallic glasses (BMGs), a versatile type of pliable glass that's stronger than steel.

User comments : 0

More news stories

Down's chromosome cause genome-wide disruption

The extra copy of Chromosome 21 that causes Down's syndrome throws a spanner into the workings of all the other chromosomes as well, said a study published Wednesday that surprised its authors.

Researchers see hospitalization records as additional tool

Comparing hospitalization records with data reported to local boards of health presents a more accurate way to monitor how well communities track disease outbreaks, according to a paper published April 16 in the journal PLOS ON ...

Ebola virus in Africa outbreak is a new strain

The Ebola virus that has killed scores of people in Guinea this year is a new strain—evidence that the disease did not spread there from outbreaks in some other African nations, scientists report.