Molecules move faster near sticky surfaces

September 1, 2017, Université libre de Bruxelles

Molecules move faster as they get closer to adhesive surfaces, but this effect is not permanent. Such is the puzzling conclusion of a study published in Physical Review Letters, carried out by Simone Napolitano and his colleagues in the Laboratory of Polymers and Soft Matter Dynamics at the Université libre de Bruxelles.

Since more than 20 years, several researchers have been studying the behaviour of certain polymers, biomolecules, and liquid crystals at the nano-scale near an absorbing medium. In this case we would expect slower rates, but the experiments showed the opposite: molecules move faster as they get closer to an adhesive . According to the research team of ULB, this odd movement is due to a phenomenon known as the 'nanoconfinement effect': the molecules that are in direct contact with the adhesive surface do move slower, or even not at all, but this in turn increases the movement rate of the next molecules, as they have more free space around them.

Now, writing in PRL, Napolitano and coworkers show that this effect is only temporary: movement rate gradually slows down as new molecules adhere to the surface and fill in the spaces left. After a while, move as if they were far from the adhesive surface. Importantly, the time necessary to return to normal molecular movement rate is longer than what would be predicted by any current theory of polymer physics.

As a result, the researchers propose that the amount of available space at the interface between polymer and sticky wall is an important parameter to control the behaviour of nanomaterials.

Explore further: Adhesive behavior of self-constructive materials measured for first time

More information: Anna Panagopoulou et al. Irreversible Adsorption Governs the Equilibration of Thin Polymer Films, Physical Review Letters (2017). DOI: 10.1103/PhysRevLett.119.097801

Related Stories

Gecko inspired adhesive can attach and detach using UV light

January 19, 2017

(Phys.org)—A small team of researchers at Kiel University in Germany has developed new technology that emulates the way a gecko uses its toes to cling to flat surfaces. In their paper published in the journal Science Robotics, ...

Physicists shatter stubborn mystery of how glass forms

June 29, 2015

A physicist at the University of Waterloo is among a team of scientists who have described how glasses form at the molecular level and provided a possible solution to a problem that has stumped scientists for decades.

The hidden order in DNA diffusion

June 7, 2017

A different approach to analyzing the motion of diffusing molecules has helped overturn the long-held assumption that DNA molecules move in a haphazard way. KAUST researchers reveal for the first time that DNA molecules move ...

Recommended for you

Pattern formation—the paradoxical role of turbulence

February 19, 2018

The formation of self-organizing molecular patterns in cells is a critical component of many biological processes. Researchers from Ludwig-Maximilians-Universitaet (LMU) in Munich have proposed a new theory to explain how ...

Bringing a hidden superconducting state to light

February 16, 2018

A team of scientists has detected a hidden state of electronic order in a layered material containing lanthanum, barium, copper, and oxygen (LBCO). When cooled to a certain temperature and with certain concentrations of barium, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.