Research axis 3

Photomechanical effects: Dr. R. Métivier, Pr. T. Kawai

Since photochromes exhibit considerable changes in shape and polarity, cohesion between photochromic units self-assembled as nanoparticles is expected to be dramatically impacted. This leads to light-triggered mechanical effects that can be harnessed to sense variations in local pressures, trigger drug delivery or organize functional nanoparticles in a contactless manner. In this task, hybrid nanomaterials will be developed by ENS Paris-Saclay and optimized to show efficient photomechanical properties, transducible to macroscopic transformations. To reach this goal, strong and reversible interactions between the nanoparticle constitutive units need to be mastered. They will imply thorough studies from collective assemblies from the micrometer scale to the single nanoparticle level. Various investigations, combining confocal and atomic force microscopies, or fluorescence and electron microscopies will be carried out, and specific effects related to the nanoscales are expected, such as low-threshold responses and amplified behaviors. Besides photomechanical properties (light stimulus, mechanical response), novel organic materials showing mechanofluorochromic properties (mechanical stimulus, light response) will be investigated at the nanoscale, with promising applications in the field of mechanical sensors and mechanobiology (PHC Sakura project 2015-2016). A very promising collaboration between ENS Paris-Saclay and Pr T. Kawai (NAIST) is starting in the field of circularly polarized luminescence with mechanofluorochromic materials. Exchange of PhD students will allow the researchers to properly study the related interactions and measure the mechanical forces by atomic force microscopy. Some Japanese students are planned also to stay in Lille Univ. to analyze the fluorescence change undergone during the molecular assembling process using multivariate methods.

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