Smart silicone coatings can change their friction and stickiness as surroundings reshape nanoscale layers
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.
A team of researchers from the University of Newcastle has developed a novel method for creating silicone surfaces that can dynamically alter their friction and stickiness based on their environment. The groundbreaking work, published in the journal Chemistry of Materials, holds significant potential for improving the performance of medical devices and other applications requiring low-friction or low-adhesion properties.
Silicone, commonly found in household products like rubbery kitchen coatings, has long been prized for its durability, water-repellent qualities, and slipperiness. However, scientists have struggled to harness silicone's potential at the nanoscale to control surface friction, particularly for use in medical devices and other high-precision applications.
To overcome this challenge, the Newcastle team employed a controlled manufacturing technique called surface-initiated controlled polymerization. This method enabled them to grow exceptionally smooth and uniform silicone brush layers with thicknesses ranging from a few nanometers to over 70 nanometers. A key discovery was that the structure of these brush layers changed dramatically depending on the surrounding liquid.
In water and simple alcohols, the polymer chains collapsed tightly against the surface, creating a thin, smooth layer. However, in liquids such as toluene and hydrocarbons—similar to those found in lubricants—the chains extended away from the surface, forming a thicker, softer layer. This solvent-regulated behavior was confirmed using advanced techniques like neutron reflectometry, ellipsometry, and atomic force microscopy.
Neutron reflectometry, in particular, proved crucial in explaining this phenomenon. By directly revealing how the polymer brush nanostructure changed in different environments, neutron reflectometry provided the missing structural insight needed to understand the unusual lubrication response of these silicone surfaces.
The researchers also demonstrated the broader implications of their work by showing how the surfaces could be produced on a larger scale. This advance opens up new possibilities for designing switchable silicone coatings whose friction and stickiness can be adjusted by simply changing the surrounding liquid. Such coatings could have wide-ranging applications, including improved lubrication in machinery, advanced industrial finishes, low-fouling surfaces, medical technologies, and microfluidic devices.
Beyond these practical applications, the study underscores the importance of understanding and controlling materials at the nanoscale to create smarter surfaces that adapt their behavior in response to changing conditions. The research was supported by ANSTO, the Australian Nuclear Science and Technology Organisation, and provided valuable opportunities for early-career researchers like first author Zachary Di Pietro, who utilized his scholarship to work with world-leading experts at the Australian Center for Neutron Scattering.
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