Polymer crystal 'turf' improves nanobrush-making process
You might not be aware of it, but invisible carpets of polymers are keeping things from being sticky right now. The lenses of your glasses might be coated with them to stave off smudges. They're keeping the underbellies of ships from corroding, artificial joints from locking up and medical devices from gathering germs. The name "polymer nanobrush" doesn't seem fitting because these bristly materials aren't used to sweep away debris, they actually prevent it from accumulating at all.
The science behind their production sounds a lot like turf management on a golf course. But for years it's been done one blade -- or bristle -- at a time, or by sprinkling some seeds and hoping for the best. Materials scientists from Drexel University have planted a new idea -- that they can make better brushes by rolling them out like sod.
Until recently, polymer brushes have been made in two main ways. One, called "grafting-from," is like sprinkling seeds on soil and waiting for grass to take root. The other, "grafting-to" is more like transplanting individual blades of grass. In a recent edition of Nature Communications, Christopher Li, PhD, a professor in Drexel's College of Engineering, explains his new method for brush making that's gives scientists a higher degree of control over the shape of the brush and bristles, and is much more efficient.
Li's approach involves growing a functional two-dimensional sheet of polymer crystals -- similar to a nanoscale piece of double-sided tape. When the sheet is stuck to an existing substrate, and the crystals are dissolved, the remaining polymer chains spring up, forming the bristles of the brush.
"The past few decades witnessed exciting progresses in studies on polymer brushes, and they show great promises in various fields, including coating, biomedical, sensing, catalysis to name just a few," said Li, whose research in the Drexel Soft Materials Lab focuses on materials that have complex structural and dynamic properties -- like polymer brushes. "We believe that our discovery of a new way to make polymer brushes is a significant advance in the field and will enable use of the brushes in exciting new ways."
Polymer brush materials are especially useful in situations where pieces need to fit tightly together but need to be able to move without friction throwing a wrench in the works. They are also effective for keeping important surfaces free of particles, chemicals, proteins and other fouling agents. Polymer brushes have been used to coat everything from eyeglass lenses, boats and medical devices -- where they keep away smudges, damaging chemicals and germs -- to artificial joints and mechanical components in vehicles -- where they act as a lubricant.
The relative amount of friction that can be reduced by the brushes has to do with how long and rigid the polymers are and how far apart they're spaced. Li's method is significant because he can precisely tune all of these characteristics because he can control the formation of the two-dimensional crystal sheets. In the paper he reports the creation of the most densely packed polymer brushes to date, with bristles less than a nanometer apart.
"These surface-functionalized 2D single crystals provide a unique opportunity for the synthesis of well-defined polymer brushes," Li said. "The key step in our method is pre-assembling polymers into polymer single crystals before coupling them onto the substrate."
For Li's group -- which has pioneered research in growing spherical crystals, and solid polymer electrolytes for energy storage -- controlling the formation of crystalized polymers for an application like this is almost second nature.
According to the paper, the team is even able to create polymer crystals with anchor points on both ends so they form a loop, which is a much sturdier bristle formation than a single-anchored polymer.
"What this all means is that one day engineers will be able to tailor-make incredibly durable polymer brush coatings to extend the usage lives of all kinds of uniquely shaped joints and couplings," Li said. "This shifts the way we look at making the brushes and I think it will have a lasting impact on this area of research."
Britt Faulstick | EurekAlert!
Researchers printed graphene-like materials with inkjet
18.08.2017 | Aalto University
Superconductivity research reveals potential new state of matter
17.08.2017 | DOE/Los Alamos National Laboratory
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences