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:6/27/2016)... - BIOREM Inc. (TSX-V: BRM) ("Biorem" or "the Company") announces ... Clean Technology Fund I, LP and Clean Technology Fund ... venture capital funds which together hold approximately 59% of ... as converted basis), that they have entered into an ... in Biorem to TUS Holdings Co. Ltd. ("TUS") (en.tusholdings.com) ...
(Date:6/27/2016)... ... June 27, 2016 , ... Cancer experts from Austria, ... could be a new and helpful biomarker for malignant pleural mesothelioma. Surviving Mesothelioma ... read it now. , Biomarkers are components in the blood, tissue or ...
(Date:6/27/2016)... (PRWEB) , ... June 27, 2016 , ... ... to bring innovative medical technologies, services and solutions to the healthcare market. The ... implementation of various distribution, manufacturing, sales and marketing strategies that are necessary to ...
(Date:6/27/2016)... , June 27, 2016  Liquid Biotech ... the funding of a Sponsored Research Agreement with ... tumor cells (CTCs) from cancer patients.  The funding ... CTC levels correlate with clinical outcomes in cancer ... data will then be employed to support the ...
Breaking Biology Technology:
(Date:4/26/2016)... and LONDON , April ... part of EdgeVerve Systems, a product subsidiary of ... today announced a partnership to integrate the Onegini ...      (Logo: http://photos.prnewswire.com/prnh/20151104/283829LOGO ) ... their customers enhanced security to access and transact ...
(Date:4/15/2016)... , April 15, 2016  A new partnership ... more accurate underwriting decisions in a fraction of ... competitively priced and high-value life insurance policies to ... With Force Diagnostics, rapid testing (A1C, ... data readings (blood pressure, weight, pulse, BMI, and ...
(Date:4/13/2016)... , April 13, 2016  IMPOWER physicians supporting Medicaid ... setting a new clinical standard in telehealth thanks to ... leveraging the higi platform, IMPOWER patients can routinely track ... and body mass index, and, when they opt in, ... convenient visit to a local retail location at no ...
Breaking Biology News(10 mins):