Home > Press > Temperature-sensitive Nanobrushes
Electrically conducting polymer with temperature-dependent optical properties and water solubility
July 13, 2005
The terms plastic and electrical current usually bring to mind such things as insulators or computer cases. It goes without saying that plastics are insulators, right? The discovery of conducting polymers actually resulted in a Nobel Prize in Chemistry for A.J. Heeger, A.G. MacDiarmid and H. Shirakawa in 2000 - "plastic electronics" are on the move. An American team has now developed a conducting polythiophene that demonstrates amazingly high water solubility and responds to the surrounding temperature as well.
Why the interest in electrically conducting polymers that are water-soluble? Water solubility allows for more environmentally friendly production processes. In addition, it is a requirement for many biological and diagnostic applications. Certain conducting polymers also respond to changes in their environment by a color change. This is just the thing for sensors that detect specific analyte molecules or indicate other parameters.
Polythiophenes, the most economically important class of conducting polymers, consist of long chains of five-membered rings containing four carbon atoms and one sulfur atom. Researchers led by Robin L. McCarley at Louisiana State University attached chains of a polyacrylamide derivative to a polythiophene backbone like bristles on the handle of a bottle brush. The "bristles" make the molecular "brushes" the most water-soluble neutral polythiophenes found to date.
But these bristles can do more: they respond sensitively to temperature changes. At temperatures under 30 °C, the brushes are in an irregular, stretched-out form and are loaded with water molecules. If the temperature is raised above 32 °C, these structures collapse into compact spheres, pushing the water molecules out. As a result, the entire brush responds to the conformational change of its bristles. From a stretched-out, only slightly balled-up form, it pulls itself into a compact spherical structure. This change decreases the water solubility of the brushes. More significantly, at the same time, the color changes; whereas a solution of the brushes at low temperature is orange-red in appearance, higher temperatures cause the color to change to yellow. This change in color indicates shifts in the electrical properties of the backbone.
Such water-soluble polymeric brushes, which react to external stimulation by changing their opto-electronic properties, could be used for biosensors in bioelectronics, as nanoswitches, light-emitting diodes, or fluorescence thermometers.
Author: Robin L. McCarley, Louisiana State University, Baton Rouge (USA),
David Greenberg (US)
Julia Lampam (UK)
Copyright © Angewandte Chemie
If you have a comment, please Contact
Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
Air Force’s 30-year plan seeks 'strategic agility' August 1st, 2014
IBM Announces $3 Billion Research Initiative to Tackle Chip Grand Challenges for Cloud and Big Data Systems: Scientists and engineers to push limits of silicon technology to 7 nanometers and below and create post-silicon future July 10th, 2014
Virus structure inspires novel understanding of onion-like carbon nanoparticles April 10th, 2014
Local girl does good March 22nd, 2014
Graphene and Amaranthus Superparamagnets: Breakthrough nanoparticles discovery of Indian researcher September 23rd, 2014
IEEE International Electron Devices Meeting To Celebrate 60th Anniversary as The Leading Technical Conference for Advanced Semiconductor Devices September 18th, 2014
Biosensors Get a Boost from Graphene Partnership: $5 Million Investment Supports Dozens of Jobs and Development of 300mm Fabrication Process and Wafer Transfer Facility September 18th, 2014
The Pocket Project will develop a low-cost and accurate point-of-care test to diagnose Tuberculosis: ICN2 holds a follow-up meeting of the Project on September 18th - 19th September 18th, 2014
Chemical interactions between silver nanoparticles and thiols: A comparison of mercaptohexanol again September 30th, 2014
A Heartbeat Away? Hybrid "Patch" Could Replace Transplants: TAU researcher harnesses gold nanoparticles to engineer novel biocompatible cardiac patch September 30th, 2014
Iranian Scientists Determine Grain Size, Minimize Time of Nanocomposite Synthesis September 29th, 2014
Nanoparticles Used to Improve Quality of Bone Cement September 29th, 2014
On the Road to Artificial Photosynthesis: Berkeley Lab Study Reveals Key Catalytic Factors in Carbon Dioxide Reduction September 25th, 2014
World's smallest reference material is big plus for nanotechnology September 25th, 2014
Quick Method Found for Synthesis of Organic Compounds with Less Pollution September 25th, 2014
Iranian Nano Scientists Create Flame-Resistant Polymers September 13th, 2014