Navigation Links
Triple threat polymer captures and releases

A chemist at Washington University in St. Louis has developed a remarkable nanostructured material that can repel pests , sweeten the air, and some day might even be used as a timed drug delivery system –as a nasal spray, for instance.

Karen L. Wooley, Ph.D., Washington University James S. McDonnell Distinguished University Professor in Arts & Sciences, has taken the same materials that she developed more than four years ago as marine "antifouling" coatings that inhibit marine organisms such as barnacles from attaching to the hull of ships to now capture fragrance molecules and release them at room temperature.

Wooley mixes two normally incompatible polymers -- a hyperbranched fluoropolymer and a linear polyethylene glycol -- and lets them phase-separate into distinct domains, one interspersed in the other. A chemical process called crosslinking then solidifies the mixture, thus creating a heterogeneous coating that, upon close examination, reveals treacherous nanometer-sized terrain composed of mountains and valleys, ranging from hard to soft, hydrophilic to hydrophobic. The complex surface that is created makes it difficult for marine organisms to establish a toehold. Her laboratory has produced these novel materials and they are being used around the world

Wooley and her collaborators were intrigued by the surface of these nanostructured materials and began to wonder what was beneath the surface. They found that their materials made a perfect host to serve guest molecules.

"We looked at the roughness and complexity of the surface and thought that the surface might provide interesting entrance and exit ports for small molecule guests," Wooley explained."So , our material would be a host that would act like a sponge, because we have this complex subsurface morphology, and we thought of it as being domains that might be like holes in sponges and other domains that might be like sponge material."

Be my guest

The subsurface composition and properties might thereby allow the guests to partition off into one domain and then another guest partition into another domain.

"We have these channels to serve as capillaries to take in guest molecules and hold them inside the material,," said Wooley, a member of Washington University's Center for Materials Innovation, (CMI) which enables collaborators from across the Washington University campus to make basic and applied advances in materials research, touching many aspects of daily life..

She and her group received a research grant from Imperial Chemical Industries/National Starch to continue their study, with a goal of taking the guest molecules in and holding them. Using the technology of thermogravimetric analysis (TGA), Gerald O. Brown, Ph.D., a postdoctoral research associate in Wooley's group, began analyzing the release of these guests ?fragrance molecules ?as gaseous small molecules from the polymer across the network of the host material.

"We found that the temperatures at which the guests left the material were dependent on the composition of the host, and when the release of the small guest molecules was monitored from just an empty TGA pan, there was a slight difference versus those guests in the presence of either the hyperbranched fluoropolymer or the polyethylene glycol," she said. "There is a slight depression of temperature at which the small molecule fragrance volatilizes and becomes a gas."

However ,when they looked at the complex materials ?the ones designed to be anti-fouling materials -- they found a progression of decreasing temperature as they went with different amounts of poly(ethylene glycol) relative to hyperbranched fluoropolymer in the composite material.

"What's amazing is that there is a 55 degree temperature reduction at which this small molecule leaves the host material versus it leaving an empty pan,, she said. "Then we thought th at this material could be very useful as something to promote the release of a volatile agent ?maybe for some kind of nasal inhalation-based delivery of drugs. Or maybe something as simple as a room temperature release of a fragrance.."

Sponge analogy

Wooley said that they don't know where the guest molecules are residing in the host material, and her group is now inserting stable isotopes into the host and guest molecules and with the help of her colleague Jacob Schaefer, Ph.D., Washington University Charles Allen Thomas Professor of Chemistry, will measure the difference between those stable isotopes to help find where the guests are located relative to the host..

"We want to know where they reside because that should tell us why this material is providing a favorable environment at room temperature but at elevated temperature for some reason everything is being expelled rapidly,," she said. "We don't know if there is some reorganization of the morphology of the material or whether the guests partition to different domains at different temperatures."

Wooley says that the results of her research with the polymers ?the promoted release, the anti-fouling application ?are "strange, if not weird, but there is so much going on here, we want to explore it all.."

That weirdness suggests equally weird mechanical properties. Wooley and her post doctoral researcher Jinqi Xu, Ph.D., are exploring those properties and one essential irony ?the material, similar to a hydrogel because it takes in water, oddly becomes stronger when water absorbs into it. Think of a soggy diaper as a hydrogel. If you liken Wooley' s materials to a diaper, that wet one becomes nearly petrified. That's known as an increased modulus value ?a measure of stress versus strain.

"When you pull on a sponge, the water comes back out," she said. "But in our case, because our sponge and the channels within it are essentially nanosco pic, the water cannot get out, at least not fast enough to allow for a reorganization of the material, and therefore it just rigidifies the material."


'"/>

Source:Washington University in St. Louis


Related biology news :

1. Triple threat: World fin trade may harvest up to 73 million sharks per year
2. Triplex assay used to assay duplex genomic DNA
3. Scientists decipher genome of fungus that can cause life-threatening infections
4. Essential mangrove forest threatened by cryptic ecological degradation
5. Simple drug has the potential to save many lives threatened by malaria
6. Alien woodwasp, threat to US pine trees, found in N.Y.
7. Poaching, logging, and outbreaks of Ebola threaten central African gorillas and chimpanzees
8. Acid water in East Java threatens biodiversity and local welfare
9. Hurricane aftermath: Infectious disease threats from common, not exotic, diseases
10. Does manganese inhaled from the shower represent a public health threat?
11. Logging doubles threat to the Amazon, rivaling clear-cutting, study suggests
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:6/20/2016)... DALLAS , June 20, 2016 ... criminal justice technology solutions for public safety, investigation, ... by the prisons involved, it has secured the ... Corrections (DOC) facilities for Managed Access Systems (MAS) ... (4) additional facilities to be installed by October, ...
(Date:6/15/2016)... New York , June 15, 2016 /PRNewswire/ ... a new market report titled "Gesture Recognition Market by ... and Forecast, 2016 - 2024". According to the report, ... USD 11.60 billion in 2015 and is estimated ... reach USD 48.56 billion by 2024.  ...
(Date:6/9/2016)... , June 9, 2016 ... Police deploy Teleste,s video security solution to ensure the safety ... France during the major tournament Teleste, ... communications systems and services, announced today that its video security ... to back up public safety across the country. ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... (PRWEB) , ... June 23, 2016 , ... ... the release of its second eBook, “Clinical Trials Patient Recruitment and Retention Tips.” ... and retention in this eBook by providing practical tips, tools, and strategies for ...
(Date:6/23/2016)... June 23, 2016 Houston Methodist Willowbrook ... Cy-Fair Sports Association to serve as their official ... Houston Methodist Willowbrook will provide sponsorship support, athletic ... with association coaches, volunteers, athletes and families. ... Cy-Fair Sports Association and to bring Houston Methodist ...
(Date:6/23/2016)... ... June 23, 2016 , ... Supplyframe, the Industry Network ... Supplyframe Design Lab . Located in Pasadena, Calif., the Design Lab’s mission is ... projects are designed, built and brought to market. , The Design Lab is ...
(Date:6/23/2016)... Andrew D Zelenetz ... Published recently in Oncology ... touchONCOLOGY, Andrew D Zelenetz , discusses the ... is placing an increasing burden on healthcare systems ... With the patents on many biologics expiring, interest ...
Breaking Biology Technology: