Process induced alignment of gold nano-rods (GNRs) in thermoplastic polymer composites with tailored optical properties

Abstract

Manipulation of the electronic and optical properties of plasmonic nanomaterials offers unique and exciting opportunities for several fields including opto-electronics, bio-medical engineering and photovoltaics. In particular, gold nanorods (GNR) represent a class of plasmonic nanomaterials that provide tunable optical properties from the visible to the near infrared regime. Herein, we have developed a highly effective method to prepare polymer nanocomposites (PNCs) doped with GNR additives utilizing extrusion and injection molding. A key outcome is that the process is amenable to scalable manufacturing and can produce highly reproducible PNCs with excellent optical properties. The resultant PNCs display good particle dispersion, minimal aggregation and a high retention of the optical properties as confirmed by UV-Vis spectroscopy and transmission electron microscopy. The nano-additives are incorporated into different thermoplastics to demonstrate the versatility of this method for different matrices and to demonstrate stability over the extrusion processing temperature range (235–335 °C). Furthermore, the tractability of this method is demonstrated by incorporating GNRs with different morphologies (aspect ratio, stabilizing layer, etc.). Finally, partial flow-induced alignment is demonstrated, the degree of which is modulated by the length and monodispersity of the GNR nano-additive. Ultimately, we report an optimized methodology to produce high quality GNR-PNCs with tailorable optical properties that can be adapted for scalable manufacturing.