News - Des nouveaux plastiques qui se réparent sous l’effet de la lumière

Des nouveaux plastiques qui se réparent sous l’effet de la lumière

Les colorants infrarouges comme outils innovants pour le remodelage et le recyclage des plastiques : Les bénéfices uniques de l’activation thermique sous irradiation proche infrarouge

Photoinduced thermal polymerization upon Near-InfraRed (NIR) light has been recently reported in the literature as an efficient tool for polymer synthesis. In these different studies, a component capable to convert a NIR light into heat (called hereafter heater) was used in combination with a thermal initiator, promoting the Free-Radical Polymerization (FRP) of acrylate monomer. In this work, a completely different approach was developed since polymeric materials containing a very low amount of a stimuli-responsive compound were prepared by using a benchmark UV photoinitiator. As the stimuli-responsive compound, an organic dye strongly absorbing in the near infrared region has been selected. The heat released by its irradiation with an inexpensive and highly penetrating (depth in the cm range) NIR light source allows the development of an unprecedented approach for reprocessing, reshaping, recycling and self-healing. For this purpose, it is important to reach a temperature higher than the glass transition temperature (T_g) of the polymeric materials, enabling then to modify their mechanical properties. Several parameters have been studied in order to determine their influence on the polymer temperature: the wavelength of the NIR irradiation, the irradiance of the NIR light source, the choice of heater (IR-813 p-toluenesulfonate or a squaraine dye) and the heater concentration. The thermoplastics bonding has also been studied and showed promising results since two pieces of polymers could be pasted together after a short time of NIR irradiation. Reversibility of the bonding was also demonstrated, still while using a NIR light as the activation source. Finally, self-healing ability of the Glyfoma-based thermoplastic was investigated and furnished impressive results even for large scratches. Notably, scratches as deep as 100 µm and with a width as large as 500 µm could be healed after only a few minutes of NIR irradiation.

Link to the Adv. Funct. Mater. article : https://doi.org/10.1002/adfm.202006324

Link to the CNRS article : https://inc.cnrs.fr/fr/cnrsinfo/des-nouveaux-plastiques-qui-se-reparent-sous-leffet-de-la-lumiere

References :

Valentin Launay, Aurore Caron, Guillaume Noirbent, Didier Gigmes, Frédéric Dumur, and Jacques Lalevée, NIR Organic Dyes as Innovative Tools for Reprocessing/Recycling of Plastics: Benefits of the Photothermal Activation in the Near‐Infrared Range. Adv. Funct. Mater. 2021, 31, 2006324