Navigation Links
'Going negative' pays for nanotubes
Date:5/3/2013

A Rice University laboratory's cagey strategy turns negatively charged carbon nanotubes into liquid crystals that could enhance the creation of fibers and films.

The latest step toward making macro materials out of microscopic nanotubes depends on cage-like crown ethers that capture potassium cations. Negatively charged carbon nanotubes associate with potassium cations to maintain their electrical neutrality. In effect, the ethers help strip these cations from the surface of the nanotubes, resulting into a net charge that helps counterbalance the electrical van der Waals attraction that normally turns carbon nanotubes into an unusable clump.

The process by Rice chemist Angel Mart, his students and colleagues was revealed in the American Chemical Society journal ACS Nano.

Carbon nanotubes have long been thought of as a potential basis for ultrastrong, highly conductive fibers a premise borne out in recent work by Rice professor and co-author Matteo Pasquali and preparing them has depended on the use of a "superacid," chlorosulfonic acid, that gives the nanotubes a positive charge and makes them repel each other in a solution.

Mart and first authors Chengmin Jiang and Avishek Saha, both graduate students at Rice, decided to look at producing nanotube solutions from another angle. "We saw in the literature there was a way to do the opposite and give the surface of the nanotubes negative charges," Mart said. It involved infusing single-walled carbon nanotubes with alkali metals, in this case, potassium, and turning them into a kind of salt known as a polyelectrolyte. Mixing them into an organic solvent, dimethyl sulfoxide (DMSO), forced the negatively charged nanotubes to shed some potassium ions and repel each other, but in concentrations too low for extruding into fibers and films.

That took the addition of ether molecules known as 18-crown-6 for their crown-like atomic arrangements. The crowns have a particular appetite for potassium; they strip the remaining ions from the nanotube walls and sequester them. The tubes' repulsive qualities become greater and allow for more nanotubes in a solution before van der Waals forces them to coagulate.

At critical mass, nanotubes suspended in solution run out of room and form a liquid crystal, Mart said. "They align when they get so crowded in the solution that they cannot pack any closer in a randomly aligned state," he said. "Electrostatic repulsions prevent van der Waals interactions from taking over, so nanotubes don't have another choice but to align themselves, forming liquid crystals."

Liquid crystalline nanotubes are essential to the production of strong, conductive fiber, like the fiber achieved with superacid suspensions. But Mart said going negative means nanotubes can be more easily functionalized -- that is, chemically altered for specific uses.

"The negative charges on the surface of the nanotubes allow chemical reactions that you cannot do with superacids," Mart said. "You may, for example, be able to functionalize the surface of the carbon nanotubes at the same time you're making fiber. You might be able to crosslink nanotubes to make a stronger fiber while extruding it.

"We feel we're bringing a new player to the field of carbon nanotechnology, especially for making macroscopic materials," he said.


'/>"/>

Contact: David Ruth
david@rice.edu
713-348-6327
Rice University
Source:Eurekalert

Related biology technology :

1. Blocked holes can enhance rather than stop light going through
2. Neuralstem President and CEO to Update Ongoing ALS and NSI-189/Major Depressive Disorder Trials at 2012 Biotech Showcase
3. New fuel cell keeps going after the hydrogen runs out
4. Sitting still or going hunting: Which works better?
5. Arnold Schwarzenegger's Climate Change Law Gets Enacted; Going Green News Site Green Bean Cleaning Urges Public to Help It Help Build a Greener Earth
6. Jennifer Aniston's People's Choice Awards Dress Worries Animal Welfare Advocates; Going Green News Site My Cleaning Products Comments It Was a Bad Pick
7. 3SBio Inc. Enters Into Merger Agreement For "Going Private" Transaction
8. Going a step Further: Phase IV and Post-Marketing Observational Studies add Value to new Therapies, life Science Webinar Hosted by Xtalks
9. New metamaterial allows transmission gain while retaining negative refraction property
10. Amsterdam Molecular Therapeutics Announces Negative Equity Position
11. Discovery opens door to low-cost negative refraction, new products and industries
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:10/9/2017)... Antonio, Texas (PRWEB) , ... ... ... new study published on October 5, 2017, in the medical journal, Epilepsia, ... equivalence with the gold standard, video EEG, in detecting generalized tonic-clonic seizures ...
(Date:10/7/2017)... ... October 06, 2017 , ... ... Hi-C metagenome deconvolution product, featuring the first commercially available Hi-C kit. Researchers ... perform Hi-C metagenome deconvolution using their own facilities, supplementing the company’s full-service ...
(Date:10/6/2017)... ... October 06, 2017 , ... The HealthTech Venture Network (HTVN) ... their fourth annual Conference where founders, investors, innovative practitioners and collaborators are invited ... competition showcasing early stage digital health and med tech companies. , This day-long ...
(Date:10/5/2017)... , ... October 05, 2017 , ... LabRoots , ... scientists from around the world, is giving back to cancer research with a month-long ... , Now through October 31, shoppers can use promo code PinkRibbon to get ...
Breaking Biology Technology:
(Date:6/30/2017)... 2017 Today, American Trucking Associations announced ... face and eye tracking software, became the newest ... "Artificial intelligence and advanced sensing ... a driver,s attentiveness levels while on the road.  ... detect fatigue and prevent potential accidents, which could ...
(Date:5/23/2017)... robotic gym for the rehabilitation and functional motor sense evaluation of lower ... . The first 30 robots will be available from June in ... The technology was developed and patented at the IIT laboratories and has ... to a 10 million euro investment from entrepreneur Sergio Dompè. ... ...
(Date:5/6/2017)... , May 5, 2017 ... just announced a new breakthrough in biometric authentication ... exploits quantum mechanical properties to perform biometric authentication. These ... smart semiconductor material created by Ram Group and ... finance, entertainment, transportation, supply chains and security. Ram ...
Breaking Biology News(10 mins):