Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Photonic gels are colorful sensors: Rice, MIT researchers create thin-film polymer metamaterial with potential for many uses

A photonic gel developed at Rice University and the Massachusetts Institute of Technology self-assembles from long polymer molecules. Polystyrene and poly(2-vinyl pyridine) are mixed in a solution that, when evaporated, allows the polymers to quickly form into nanosized layers. The layers can be tuned to reflect specific colors when exposed to particular chemicals. Joseph Walish/MIT
A photonic gel developed at Rice University and the Massachusetts Institute of Technology self-assembles from long polymer molecules. Polystyrene and poly(2-vinyl pyridine) are mixed in a solution that, when evaporated, allows the polymers to quickly form into nanosized layers. The layers can be tuned to reflect specific colors when exposed to particular chemicals.

Joseph Walish/MIT

Abstract:
Materials scientists at Rice University and the Massachusetts Institute of Technology (MIT) have created very thin color-changing films that may serve as part of inexpensive sensors for food spoilage or security, multiband optical elements in laser-driven systems and even as part of high-contrast displays.

Photonic gels are colorful sensors: Rice, MIT researchers create thin-film polymer metamaterial with potential for many uses

Houston, TX | Posted on October 10th, 2012

The new work led by Rice materials scientist Ned Thomas combines polymers into a unique, self-assembled metamaterial that, when exposed to ions in a solution or in the environment, changes color depending on the ions' ability to infiltrate the hydrophilic (water-loving) layers.

The research was published in the American Chemical Society journal ACS Nano.

The micron-thick material called a photonic gel, far thinner than a human hair, is so inexpensive to make that, Thomas said, "We could cover an area the size of a football field with this film for about a hundred dollars."

But for practical applications, much smaller pieces would do. "Suppose you want a food sensor," said Thomas, the William and Stephanie Sick Dean of Rice's George R. Brown School of Engineering and former chair of the Department of Materials Science and Engineering at MIT. "If it's inside a sealed package and the environment in that package changes because of contamination or aging or exposure to temperature, an inspector would see that sensor change from blue to red and know immediately the food is spoiled."

Such visual cues are good, he said, "especially when you need to look at a lot of them. And you can read these sensors with low tech, either with your own eyes or a spectrophotometer to scan things."

The films are made of nanoscale layers of hydrophobic polystyrene and hydrophilic poly(2-vinyl pyridine). In the liquid solution, the polymer molecules are diffused, but when the liquid is applied to a surface and the solvent evaporates, the block copolymer molecules self-assemble into a layered structure.

The polystyrene molecules clump together to keep water molecules out, while the poly(2-vinyl pyridine), P2VP for short, forms its own layers between the polystyrene. On a substrate, the layers form into a transparent stack of alternating "nano-pancakes." "The beauty of self-assembly is that it's simultaneous, all the layers forming at once," Thomas said.

The researchers exposed their films to various solutions and found different colors depending on how much solvent was taken up by the P2VP layers. For example with a chlorine/oxide/iron solution that is not readily absorbed by the P2VP, the film is transparent, Thomas said. "When we take that out, wash the film and bring in a new solution with a different ion, the color changes."

The researchers progressively turned a clear film to blue (with thiocyanate), to green (iodine), to yellow (nitrate), to orange (bromine) and finally to red (chlorine). In each case, the changes were reversible.

Thomas explained that the direct exchange of counterions from the solution to the P2VP expands those layers and creates a photonic band gap — the light equivalent of a semiconducting band gap - that allows color in a specific wavelength to be reflected. "The wavelengths in that photonic band gap are forbidden to propagate," he said, which allows the gels to be tuned to react in specific ways.

"Imagine a solid in which you create a band gap everywhere but along a 3-D path, and let's say that path is a narrowly defined region you can fabricate within this otherwise photonic material. Once you put light in that path, it is forbidden to leave because it can't enter the material, due to the band gap.

"This is called molding the flow of light," he said. "These days in photonics, people are thinking about light as though it were water. That is, you can put it in these tiny pipes. You can turn light around corners that are very sharp. You can put it where you want it, keep it from where you don't want it. The plumbing of light has been much easier than in the past, due to photonics, and in photonic crystals, due to band gaps."

Co-authors of the paper are Rice research scientist Jae-Hwang Lee and MIT postdoctoral researchers Ho Sun Lim and Joseph Walish.

The work was supported by the U.S. Army Research Office, the U.S. Air Force and the Korea Research Foundation, funded by the Korean government.

####

About Rice University
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,708 undergraduates and 2,374 graduate students, Rice’s undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice has been ranked No. 1 for best quality of life multiple times by the Princeton Review and No. 4 for “best value” among private universities by Kiplinger’s Personal Finance. To read “What they’re saying about Rice,” go to www.rice.edu/nationalmedia/Rice.pdf.

Follow Rice News and Media Relations via Twitter @RiceUNews

For more information, please click here

Contacts:
Mike Williams
713-348-6728

Copyright © Rice University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Iran to Hold 3rd Int'l Engineering Materials, Metallurgy Conference October 25th, 2014

Haydale Secures Exclusive Development and Supply Agreement with Tantec A/S: New reactors to be built and commissioned by Tantec A/S represent another step forward towards the commercialisation of graphene October 24th, 2014

QuantumWise guides the semiconductor industry towards the atomic scale October 24th, 2014

SUNY Polytechnic Institute Invites the Public to Attend its Popular Statewide 'NANOvember' Series of Outreach and Educational Events October 23rd, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

Thin films

Advancing thin film research with nanostructured AZO: Innovnano’s unique and cost-effective AZO sputtering targets for the production of transparent conducting oxides October 23rd, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

NIST offers electronics industry 2 ways to snoop on self-organizing molecules October 22nd, 2014

Display technology/LEDs/SS Lighting/OLEDs

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

Legal

SUNY CNSE and Albany Law School Partner to Create First-of-its-Kind Nanotechnology Education and Training Program November 5th, 2013

US Court of Appeals characterizes Wyatt Technology Corporation Lanham Act claims as “groundless, unreasonable, vexatious or pursued in bad faith” May 31st, 2013

Fluidigm Files Lawsuit against NanoString’s Deceptive Marketing: Fluidigm Sues NanoString for False and Misleading Advertising under the Lanham Act November 8th, 2012

FBI seminar educates about research protection July 31st, 2012

Govt.-Legislation/Regulation/Funding/Policy

Novel Rocket Design Flight Tested: New Rocket Propellant and Motor Design Offers High Performance and Safety October 23rd, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

Brookhaven Lab Launches Computational Science Initiative:Leveraging computational science expertise and investments across the Laboratory to tackle "big data" challenges October 22nd, 2014

Bipolar Disorder Discovery at the Nano Level: Tiny structures found in brain synapses help scientists better understand disorder October 22nd, 2014

Self Assembly

NYU Researchers Break Nano Barrier to Engineer the First Protein Microfiber October 23rd, 2014

NIST offers electronics industry 2 ways to snoop on self-organizing molecules October 22nd, 2014

‘Designer’ nanodevice could improve treatment options for cancer sufferers October 22nd, 2014

Crystallizing the DNA nanotechnology dream: Scientists have designed the first large DNA crystals with precisely prescribed depths and complex 3D features, which could create revolutionary nanodevices October 20th, 2014

Discoveries

QuantumWise guides the semiconductor industry towards the atomic scale October 24th, 2014

Iranian, Malaysian Scientists Study Nanophotocatalysts for Water Purification October 23rd, 2014

Nanoparticle technology triples the production of biogas October 23rd, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

Materials/Metamaterials

Iran to Hold 3rd Int'l Engineering Materials, Metallurgy Conference October 25th, 2014

Researchers patent a nanofluid that improves heat conductivity October 22nd, 2014

Materials for the next generation of electronics and photovoltaics: MacArthur Fellow develops new uses for carbon nanotubes October 21st, 2014

Super stable garnet ceramics may be ideal for high-energy lithium batteries October 21st, 2014

Announcements

Iran to Hold 3rd Int'l Engineering Materials, Metallurgy Conference October 25th, 2014

Haydale Secures Exclusive Development and Supply Agreement with Tantec A/S: New reactors to be built and commissioned by Tantec A/S represent another step forward towards the commercialisation of graphene October 24th, 2014

QuantumWise guides the semiconductor industry towards the atomic scale October 24th, 2014

Strengthening thin-film bonds with ultrafast data collection October 23rd, 2014

Military

NanoTechnology for Defense (NT4D) October 22nd, 2014

Crystallizing the DNA nanotechnology dream: Scientists have designed the first large DNA crystals with precisely prescribed depths and complex 3D features, which could create revolutionary nanodevices October 20th, 2014

Imaging electric charge propagating along microbial nanowires October 20th, 2014

1980s aircraft helps quantum technology take flight October 20th, 2014

Food/Agriculture/Supplements

Smallest world record has 'endless possibilities' for bio-nanotechnology October 8th, 2014

Simple Detection of Toxic Compounds in Dairy Products October 6th, 2014

Iranian Scientists Separate Zinc Ion at Low Concentrations September 20th, 2014

Nanoscience makes your wine better September 17th, 2014

Photonics/Optics/Lasers

Physicists build reversible laser tractor beam October 20th, 2014

Magnetic mirrors enable new technologies by reflecting light in uncanny ways October 16th, 2014

New VDMA Association "Electronics, Micro and Nano Technologies" founded: Inaugural Meeting in Frankfurt/Main, Germany October 15th, 2014

Nanodevices for clinical diagnostic with potential for the international market: The development is based on optical principles and provides precision and allows saving vital time for the patient October 15th, 2014

Research partnerships

NYU Researchers Break Nano Barrier to Engineer the First Protein Microfiber October 23rd, 2014

Nanoparticle technology triples the production of biogas October 23rd, 2014

RF Heating of Magnetic Nanoparticles Improves the Thawing of Cryopreserved Biomaterials October 23rd, 2014

Brookhaven Lab Launches Computational Science Initiative:Leveraging computational science expertise and investments across the Laboratory to tackle "big data" challenges October 22nd, 2014

NanoNews-Digest
The latest news from around the world, FREE





  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE