Category Archives: Collaborations

Tribology – New paper in JPC A


Tribology isn’t exactly an area with which us chemists are most familiar, yet chemistry has a great impact on this branch of physics of high industrial importance. Tribology is basically the science which studies the causes and consequences of friction between surfaces. 

The plastic bag industry requires the use of chemical additives to reduce the electrostatic adherence between sheets of plastic. My good old friend Dr. Armando Gama has studied through Dissipative Particle Dynamics (DPD) coarse-grained simulations the friction coefficients of having two slightly different molecules: erukamide and behenamide, which only differ in the presence of a double bond between carbon atoms 12 and 13 (Fig1).

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Fig 1

In order to study the electronic aspects that give rise to different tribological effects in these very similar molecules, four chains of each kind were bounded to a frozen graphene surface (four bonds apart to prevent steric crowding) and were optimized at the B97D/6-31G(d,p) level of theory.

 

 

Double bonds in erukamide pile together through pi-pi stacking interactions (Fig2) which are absent in behenamide which is why these last ones are able to slide better between each other (Fig3). Interaction energies calculated for the inner chains at the same level of theory are 44.21 and 34.46 kcal/mol for erukamide and behenamide, respectively. As per the suggestion of a referee we extended the calculations to a 2D system by placing seven molecules on graphene, which once again was kept at the optimized geometry of its isolated state, at four bonds of separation in order to prevent steric crowding (Fig 4).

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Fig 4

This calculations clearly represent a limit case with a high density covering of the surface, but they nevertheless reflect the observed trend that behenamide works better than erukamide in reducing the static friction coefficient between sheets.

The paper is now available at JPC-A. Thanks to Dr. Gama for this great opportunity to work with his team, I know it wont be the last.

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Back in Pécsi Tudomanyegyetem (Hungary)


I’m so glad to be back in Pécs, Hungary, at the lab of my good old friend Prof. Dr. Sándor Kunsági. It has been seven years since I was last here and so many things have happened and yet it feels like yesterday I was walking through these halls.

As part of an agreement between the science councils of both Mexico and Hungary, our research proposal on the development of macrocyclic-based therapeutic agents for capturing micotoxins and other molecules was selected for financing. As before, the theoretical section will be handled by us, namely to some extent by Marco Diaz as part of his BSc thesis, while the experimental part will be handled by the group from Prof. Kunsagi’s lab and Dr. Lemli Beáta‘s. I’m very excited about living for a month here in Pécs but also about having a close friend, to whom I owe so much, working with me in an experimental-theoretical project that will further advance both our researches and careers. It was in fact the work of Profs. Kunsagi here in Pécs and Silaghi in Cluj, Romania, which got me interested in the supramolecular chemistry of calixarenes.

Lets hope we can manage to keep this collaboration between our labs going on for many years to come. For the sake of humor here are some old and new photographs.

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