This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Research led by a group from the University of Newcastle has found a new way to make silicone surfaces—and control how slippery they are. The work was published in the journal Chemistry of Materials.
Most of us have silicone in our homes, especially in the kitchen, where it is often found as a rubbery coating that is long-lasting, water-repellent and, crucially, slippery. Scientists have also wanted to make use of it at the nanoscale, where silicone has significant potential to reduce surface friction for use in medical devices and beyond. Because silicone is made up of long molecules, known as polymers, scientists have hoped to make surfaces where these molecules are arranged like a brush.
But silicone brush surfaces have been very hard to make, and their surface properties have been difficult to control. Using a controlled manufacturing technique called surface-initiated controlled polymerization, the team grew exceptionally smooth and uniform silicone brush layers. The thickness of the brushes could be tuned from only a few nanometers to more than 70 nanometers.
A key discovery was that the structure of these brushes changes dramatically depending on the surrounding liquid. In water and simple alcohols, the polymer chains collapse tightly against the surface. In liquids such as toluene and hydrocarbons, similar to those found in lubricants, the chains take up solvent and extend away from the surface, creating a thicker, softer layer.
To confirm their discovery, the researchers combined neutron reflectometry on the Platypus instrument at the Australian Center for Neutron Scattering with ellipsometry and atomic force microscopy measurements. Together, these techniques showed how the brushes "grew," how their internal structure responded to different liquids and how those changes affected friction and adhesion. "Neutron scattering was essential to explain this behavior.
Neutron reflectometry directly revealed how the polymer brush nanostructure changes in different environments, providing the missing structural insight needed to understand the unusual lubrication response," said principal investigator Dr. Edwin Johnson from the University of Newcastle. The work also demonstrates ANSTO's support of early-career researchers.
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