Navigation Links
Energy squeeze
Date:3/2/2012

A polymer is a mesh of chains, which slowly break over time due to the pressure from ordinary wear and tear. When a polymer is squeezed, the pressure breaks chemical bonds and produces free radicals: ions with unpaired electrons, full of untapped energy. These molecules are responsible for aging, DNA damage and cancer in the human body.

In a new study, Northwestern University scientists turned to squeezed polymers and free radicals in a search for new energy sources. They found incredible promise but also some real problems. Their report is published by the journal Angewandte Chemie.

The researchers demonstrated that radicals from compressed polymers generate significant amounts of energy that can be used to power chemical reactions in water. This energy has typically been unused but now can be harnessed when polymers are under stress in ordinary circumstances -- as in shoe soles, car tires or when compacting plastic bags.

They also discovered during the study that a silicone polymer commonly used in implants for cosmetic procedures releases a large quantity of harmful free radicals when the polymer is under only a moderate amount of pressure. These findings suggest the safety of certain polymer-based medical implants should be looked at more closely.

"We have established that polymers under stress create free radicals with overall efficiencies of up to 30 percent and shoot the radicals out into the surrounding medium where they can drive chemical reactions," said Bartosz A. Grzybowski, an author of the paper and the Kenneth Burgess Professor of Physical Chemistry and Chemical Systems Engineering. "These radicals can be useful or they can be harmful, depending on the situation."

Grzybowski and his team are the first to use this energy to drive chemical reactions by simply surrounding the compressed polymer with water containing desired reagents.

The radicals created in the polymer migrate toward the polymer/water interface where they produce hydrogen peroxide, which then can drive chemical processes.

"You can get a surprisingly large amount of chemical energy from a polymer under compression," Grzybowski said. "This energy is, in a sense, free for the taking. Under normal circumstances, the energy is virtually never retrieved from deformed polymers, which then age unproductively. But you could recharge a battery from the energy produced by walking or driving a car. And you could capture even more energy when compacting millions of plastic bags."

Grzybowski is also director of Northwestern's Non-Equilibrium Energy Research Center, which is funded by the U.S. Department of Energy.

"We are interested in new sources of chemical energy, and this energy from the simple breaking of polymers' bonds is not being used," he said. "By surrounding the polymer with a medium, such as water, we can produce environmentally friendly chemical energy. One direction we are pursuing is to use this energy to sanitize water in developing countries. This is possible because hydrogen peroxide produced by squeezed polymers kills bacteria."

The researchers confirmed that mechanical deformation -- moderate squeezing -- created free radicals in the polymers. They also determined the number of radicals produced in a polymer under pressure is approximately 1016 (10 to the 16th) radicals per cubic centimeter of polymer -- a substantial amount.

They next filled polymer tubes with water, squeezed the tubes and measured the total number of radicals that migrated into the surrounding solution. They found that nearly 80 percent of the radicals made the trip.

Grzybowski and his team demonstrated they can squeeze a polymer, such as what might be found in a shoe, tire or plastic bag, and get a mechanical-to-chemical energy conversion of up to 30 percent -- approaching the energy efficiency of a car engine.

The hydrogen peroxide produced when a polymer surrounded by water is squeezed can power a variety of chemical reactions, including fluorescence, nanoparticle synthesis and dye bleaching, the researchers showed.

To illustrate the process, they converted a Nike Air LeBron shoe into a "lightning shoe," where the air pockets in the polymeric sole are filled with a solution of a compound that lights up in the presence of radicals. After a person walked in the shoe for 30 minutes or more, enough radicals were created to generate a blue glow visible to the naked eye.

The researchers studied seven different polymers, including a number of particular public interest. Poly(dimethylsiloxane), a silicon-based material commonly used in medical implants, was one of them. In the lab experiments, the medium surrounding the polymer and the amount of pressure exerted on the material were similar to what would be found in the human body, Grzybowski pointed out.

"Our findings are somewhat worrisome since every polymeric implant in the human body experiences mechanical stresses and, as we now know, can produce harmful free radicals and liberate them into surrounding tissues, which may contribute to diseases such as cancer, stroke, myocardial infarction, diabetes and other major disorders," Grzybowski said. "With this knowledge, I am quite happy to have a metal implant in my knee, rather than a polymer implant.

"From a scientific perspective, our work proves yet again that a phenomenon can be useful or harmful depending on how we implement it," he said. "The same polymer can be a useful source of energy when outside of a human body, yet a potential risk hazard when implanted into it."


'/>"/>
Contact: Megan Fellman
fellman@northwestern.edu
847-491-3115
Northwestern University
Source:Eurekalert

Related medicine news :

1. Cell energy sensor mechanism discovered
2. Energy network within cells may be new target for cancer therapy
3. Decaffeinated coffee preserves memory function by improving brain energy metabolism
4. ER Visits for Energy-Drink Ills Soar in U.S.
5. Cavemen Knew It: Cooked Meat Offers More Energy
6. Molecular depth profiling modeled using buckyballs and low-energy argon
7. Medieval Armor Drained Soldiers Energy, Study Finds
8. Energy drinks linked to substance use in musicians, study shows
9. Energy Drink-Vodka Combo Nearly Kills Teen
10. Pediatricians Group Raps Energy and Sports Drinks for Kids
11. Dual-energy CT may be useful in evaluating the severity of gout, study suggests
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/26/2016)... ... , ... Despite last week’s media reports hinting at a June rate hike ... March 2017 for an interest rate increase, according to Rajeev Dhawan of the Economic ... Federal Open Market Committee (FOMC) dot charts are of interest to the press for ...
(Date:5/26/2016)... (PRWEB) , ... May 26, 2016 , ... ... and clinical outcomes, hosted members and suppliers for its inaugural Member Conference at ... on their mission of elevating the operational health of America’s healthcare providers. , ...
(Date:5/26/2016)... ... May 26, 2016 , ... The Woodlands at ... offering a new model of care for living and healing, celebrated its grand opening, ... Life in a Real Home provided by Empowered Staff. , “This is an incredibly ...
(Date:5/26/2016)... ... May 26, 2016 , ... Catalent Pharma Solutions, ... biologics, consumer health and global clinical supply services, today announced two key appointments ... company’s continued investment and strategic growth plans in the Asia Pacific region. , ...
(Date:5/26/2016)... , ... May 26, 2016 , ... Memorial Day Weekend ... Amica Insurance is sharing tips to make sure your family and vehicle ... the National Safety Council, there may be 439 deaths and an additional 50,500 serious ...
Breaking Medicine News(10 mins):
(Date:5/24/2016)... AMSTERDAM , May 24, 2016 ... auf den Markt gebracht, die es Ärzten erlaubt, ... überall zu behandeln: MDLinking kombiniert Live Streaming mit ... sicheren Umfeld zu kommunizieren. Mediziner in Europa, Afrika, ... haben sich bereits für die Plattform registriert. ...
(Date:5/24/2016)... 2016  Diana Russell suffers from a form of ... inside out.  This disease has put her in a ... and grandchildren to leave her home.  Because of the ... haul the wheelchair.  So if there is a family ... is left to wait for the bus. ...
(Date:5/24/2016)... has joined VMS BioMarketing as senior vice president of sales, announced Andrea Heslin ... will lead the company,s business development and sales team, exploring new opportunities for VMS ... http://photos.prnewswire.com/prnh/20160523/371089 ... ... ...
Breaking Medicine Technology: