In situ synthesis of plasmonic and magnetic nanoparticles in polymer thin films under laser and solar irradiation

Plasmonic and magnetic nanocomposite materials are of great interest in many applications such as photonics, photovoltaics, catalysis, medicine and biology. This field has been the subject of a large activity in the past... [ view full abstract ]

Plasmonic and magnetic nanocomposite materials are of great interest in many applications such as photonics, photovoltaics, catalysis, medicine and biology. This field has been the subject of a large activity in the past decades. At the same time, chemists have demonstrated the versatility of wet synthesis approaches to fabricate nanoparticles with well-defined magnetic and optical properties. However, the insertion in matrices of such nanostructures on a large scale and at high concentrations in view of applications is still challenging. In order to address this issue, we propose two new approaches, based on the in situ synthesis of nanoparticles in polymer thin films under irradiation. In the first approach, our aim is to control the spatial organization of the nanoparticles within the polymer films by laser interferometry. We show that the plasmonic nanoparticle gratings thus formed present unusual diffractive properties that strongly depend on the plasmonic excitation of the system. In the second method, we study the in situ synthesis of nanoparticles in polymer thin films under concentrated solar irradiation. We show that this technique can be used as an efficient route for the fabrication of both plasmonic and magnetic nanocomposite thin films. In particular, we study for the first time the synthesis of magnetic nanoparticles under visible-light irradiation and without the use of chemical reducing agent to initiate the nanoparticle formation. This approach can be readily used for large-scale production and allows for the insertion of large metal filling fractions in the polymer films while keeping the nanoparticles from agglomeration. Moreover, in the case of plasmonic nanoparticles, we found that adjusting irradiation conditions, and especially the light flux, affects the size and morphology of the nanoparticles. Finally, we have successfully tested this approach by using biopolymer as matrices, thus meeting the requirements of green synthesis.