While they have proven useful for these purposes, no one really knows much about what’s going on at the molecular level. For example, how do nanotubes and chemical functional groups interact with each other on the atomic scale? Answering this question could lead to improvements in future nano devices.
In a quest to find the answer, researchers for the first time have been able to measure a specific interaction for a single functional group with carbon nanotubes using chemical force microscopy – a nanoscale technique that measures interaction forces using tiny spring-like sensors. Functional groups are the smallest specific group of atoms within a molecule that determine the characteristic chemical reactions of that molecule.
A recent report by a team of Lawrence Livermore National Laboratory researchers and colleagues found that the interaction strength does not follow conventional trends of increasing polarity or repelling water. Instead, it depends on the intricate electronic interactions between the nanotube and the functional group.
“This work pushes chemical force microscopy into a new territory,” said Aleksandr Noy, lead author of the paper that appears in the Oct. 14 online issue of the journal, Nature Nanotechnology.
Understanding the interactions between carbon nanotubes (CNTs) and individual chemical functional groups is necessary for the engineering of future generations of sensors and nano devices that will rely on single-molecule coupling between components. Carbon nanotubes are extremely small, which makes it particularly difficult to measure the adhesion force of an individual molecule at the carbon nanotube surface. In the past, researchers had to rely on modeling, indirect measurements and large microscale tests.
But the Livermore team went a step further and smaller to get a more exact measurement. The scientists were able to achieve a true single function group interaction by reducing the probe-nanotube contact area to about 1.3 nanometers (one million nanometers equals one millimeter).
Adhesion force graphs showed that the interaction forces vary significantly from one functionality to the next. To understand these measurements, researchers collaborated with a team of computational chemists who performed ab initio simulations of the interactions of functional groups with the sidewall of a zig-zag carbon nanotube. Calculations showed that there was a strong dependence of the interaction strength on the electronic structure of the interacting molecule/CNT system. To the researchers delight, the calculated interaction forces provided an exact match to the experimental results.
“This is the first time we were able to make a direct comparison between an experimental measurement of an interaction and an ab initio calculation for a real-world materials system,” Noy said. “In the past, there has always been a gap between what we could measure in an experiment and what the computational methods could do. It is exciting to be able to bridge that gap.”
This research opens up a new capability for nanoscale materials science. The ability to measure interactions on a single functional group level could eliminate much of the guess work that goes into the design of new nanocomposite materials, nanosensors, or molecular assemblies, which in turn could help in building better and stronger materials, and more sensitive devices and sensors in the future.
Source: Lawrence Livermore National Laboratory
Related stories:
Autism's social struggles due to disrupted communication networks in brain
Picking up on innuendo and social cues is a central component of engaging in conversation, but people with autism often struggle to determine another person's intentions in a social interaction. New research from Carnegie Mellon University sheds light on the neural mechanisms that are responsible for such social difficulties in autism, and on the workings of these social brain mechanisms in all of us.
Children are naturally prone to be empathic and moral
Children between the ages of seven and 12 appear to be naturally inclined to feel empathy for others in pain, according to researchers at the University of Chicago, who used functional Magnetic Resonance Imaging (fMRI) scans to study responses in children.
A better image for plastic solar cells
A new way to help technologists develop efficient and inexpensive plastic electronic devices, such as plastic solar cells and a new type of transistor was showcased by physicist Andrea Liscio, who is supported by the European Science Foundation, at the EMRS (European Material Research Society) Spring Meeting held in Strasbourg, France at the end of May.
Mechanism explains calcium abnormalities in Alzheimer's brain
A new study uncovers a mechanism that directly links mutations that cause early onset Alzheimer's disease (AD) with aberrant calcium signaling. The research, published by Cell Press in the June 26th issue of the journal
Neuron, provides exciting molecular insights into the pathology of AD and may lead to new treatment strategies.
Designing semantic software by numbers
A system for creating semantic software could transform application development from a cottage industry to an industrial-style production line. Semantic applications are the next frontier for information science, but creating them is very difficult.
Natural plant materials to regulate starch digestion
Researchers in Switzerland are reporting discovery of natural plant materials that may regulate starch digestion — slowing down the body's conversion of potatoes, rice, and other carbohydrate-rich foods into sugar. The findings could lead to new functional foods that fight diabetes, they say in a report scheduled for the June 26 issue of the ACS' bi-weekly
Journal of Medicinal Chemistry.
New research shows how aging brain brings a healthy dose of perspective
A University of Alberta researcher in collaboration with researchers from Duke University has proven that wisdom really does come with age, at least when it comes to your emotions.
Brain's 'trust machinery' identified
The brain centers triggered by a betrayal of trust have been identified by researchers, who found they could suppress such triggering and maintain trust by administering the brain chemical oxytocin. The researchers said their findings not only offer basic insights into the neural machinery underlying trust; the results may also help in understanding the neural basis of social disorders such as phobias and autism.
