Feb 17 2017
CNR researchers show that it is possible to obtain a very low cost fotomobili polymers to study the conversion of light into mechanical work. The results published in Advanced Materials
The Marangoni effect is known from more than 140 years and is responsible for the movement of objects on a liquid due to the change of its surface tension. Among insects there are notable examples of how living organisms can take advantage of this effect to generate a controlled movement.
In relatively recent times it has been observed as the Marangoni effect may also be induced by light, illuminating objects whose edges are highly absorbent -because covered with nanotubes, for example- or moving objects on highly absorbent liquid, illuminating the liquid in proximity to the 'object you want to move.
A research developed and conducted by Riccardo Castagna of Isasi-CNR team coordinated by Lucia Petti, and conducted in collaboration with other researchers including Daniel E. Lucchetta and Francesco Simoni Polytechnic University of Marche (UNIVPM), reveals a new way to use the Marangoni effect induced by light.
It concerns the realization of thin films of polymer that represent portions of two parts: a skeleton which tends to maintain the original shape of the film (in turn constituted by an outer layer rather rigid and an inner layer that has the form of micrometric bristles) and a second part practically in contact with the bristles of the skeleton, made up of a rather viscous liquid (motor) which, for Marangoni effect induced by light, tends to 'escape' from the skeleton. The affinity between the two parties allows the engine to drag the skeleton under illumination (the film bending) while, in light off, the film reconstructs and restores its original shape. The research was published in Advanced Materials (Impact Factor of 18.96), one of the most important magazines in the world for the study of materials.
The fotomobili polymers are already known in the literature: the most advanced are based on the integration of azobenzenes in liquid-crystalline polymers. Their synthesis is very expensive and requires a considerable number of steps. In the case proposed by CNR researchers, the synthesis is carried out in one step, through a particular process of photopolymerization of a mixture of multiacriati and vinyl materials at very low cost. "This photo-mobile films will permit many more groups of rcerca to study the conversion of photons into mechanical work, because it is easily obtainable and low costs. In addition, it should open up significant prospects in the field of sensor technology: in fact we are already using for plasmonic devices for nano-sensing "confirms the researcher Riccardo Castagna.