Macroscopic Alignment of Silver Nanoplates in an Adaptable Dichroic Polarizer

Abstract

Morphological control to precisely tailor the energy absorption bands of plasmonic particles is improving constantly, with efforts to improve the monodispersity of the designed particles leading to sharper plasmonic features in controlled spectral regions. Transitioning these highly tailored plasmonic additives into a robust polymer composite platforms while retaining their specified plasmonic features has proven challenging, with the elevated temperatures and mechanical forces involved in composite manufacturing resulting in particle agglomeration and morphology alterations. In this work, thermally stable protecting layers are developed onto tailored silver nanoplate (Ag-NPL) plasmonic additives to facilitate their survivable processing at elevated temperature. The produced coatings allow for their implementation in a facile, low-cost method to produce uniform dichroic optical polarizers based on the protected Ag-NPLs in a polymer matrix. Nanocomposites are obtained through an extrusion and injection molding process, which is shown to induce alignment of anisotropic particles based on sheer forces. As the optical position of the resonances is dependent on the morphology of the additive, and unlike other methods where the anisotropy in the NP is induced in situ, our method can be easily adapted to varying optical regimes by modifying the size and shape of the initial additive. Furthermore, the method presented in this work forgoes the need for a polymer stretching alignment mechanism which enables the ability to use various types of anisotropic particles with visible and near-infrared operating regimes.