Historical background

Janus particles are dissymmetric particles named in reference to the Roman god Janus, usually represented with one head but two faces. Janus particles are micro- or nano-objects with two sides having different properties.

A new process developed in our group can modify any conductive object, from micrometer to sub-micrometer scale with a large spectrum of materials to form a dissymmetric particle. For example, a particle may have both hydrophilic and hydrophobic properties.

This unique feature allows the fabrication of micro or nano-objects comprising two regions of different polarity or chemical activity. There is an increase of scientific and industrial interest in such Janus particles. Such particles can be used in a wide range of applications like catalysis, therapeutic treatments, textiles, food processing, sensors, imaging… Unfortunately, because of their unique architecture, the synthesis of Janus particles remains a challenge.

The process

The technology is based on a patent filed at the end of 2010 by the University Bordeaux I, the Polytechnic Institute of Bordeaux and the CNRS (National Center for Scientific Research). Our group was firstly able to develop a laboratory reactor which produces quantities of these Janus particles covered with metal, carbon or conductive polymers at the milligram-scale. The team then proceeded to manufacture a prototype to obtain production at a larger scale.

This new process can modify any conductive object, submicrometer to micrometer scale with a wide range of materials to form a dissymmetrical particle, overcoming the drawbacks of the methods known to date. The technical implementation is three dimensional and has a great flexibility, which enables a wide range of Janus particles to be formed in terms of materials, sizes, shapes and types.

The process which was finalized by the laboratory leads to Janus bifunctional particles with these specificities:

Size: from 100 nm up to 200 microns
Shapes: isotropic or anisotropic

A quick summary of the technology is described in the video below :

We propose a new process based on bipolar Electrochemistry. We can modify any conductive nano-object to a dissymmetrical and bifunctional nano-object. Breaking symmetry in physical, chemical and biological systems is very useful: Electronic Paper displays (especially electronic ink), Nanoelectronics, chemical catalysis, stabilization of emulsions, Medicine, Photovoltaics. Beyond the immediate applications, Janus particles are generally of great interest to the scientific community, as highlighted by recent work on fundamental phenomena such as directed self-assembly, electron transport in nano-objects or behavior of optical quantum dots. Proposing a simple method to make custom objects can provide asymmetric objects of study for the scientific community, which will enable new phenomena and applications to be developed.

If you are interested in using this technology for a specific application and want to know more about it, please contact us or have a look at the dedicated website done in collaboration with Aquitaine Science Transfert, the regional branch of the Structure for Accelerating Technology Transfer.

To know more about the technology, feel free to read the article recently published in International Innovation.

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ISM - Groupe NSysA - Site ENSCBP
16, avenue Pey Berland - 33600 Pessac, FR
T (33) 5 40 00 22 39
F (33) 5 40 00 27 17
Email: nsysa.ism@u-bordeaux.fr

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