Efficient way to make polymer nanobrush developed

Scientists have developed a more efficient technique for creating polymer nanobrushes - tiny, bristly structures that repel dirt and prevent it from accumulating on the surface.
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.
These bristly materials are not used to sweep away debris, they actually prevent it from accumulating at all, researchers said.
For years, their production has been done one blade - or bristle - at a time, or by sprinkling some seeds and hoping for the best, they said.

Now, scientists from Drexel University in the US 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.
Christopher Li from Drexel's College of Engineering developed a new method for brush making that gives scientists a higher degree of control over the shape of the brush and bristles, and is much more efficient.
The approach involves growing a functional two-dimensional sheet of polymer crystals - similar to a nanoscale piece of double-sided tape, Li said.

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, he said.
"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," said Li.
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, researchers said.
They are also effective for keeping important surfaces free of particles, chemicals, proteins and other fouling agents, they said.

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 are spaced.
Li's method is significant because he can precisely tune all of these characteristics as he can control the formation of the two-dimensional crystal sheets, researchers said.
"These surface-functionalised 2D single crystals provide a unique opportunity for the synthesis of well-defined polymer brushes," said Li.
"The key step in our method is pre-assembling polymers into polymer single crystals before coupling them onto the substrate," he said.
The findings were published in the journal Nature Communications.