Polylactic acid 3D interconnected nanonetworks as high reflectance distributed Bragg reflectors

Abstract

Natural systems found ways to exploit light at the nanoscale, devising complex 3D structures that behave as photonic crystals, able to produce structural coloration. Distributed Bragg reflectors are a particular example of 1D photonic crystals, used in different applications, including structural coloration. Currently distributed Bragg reflectors rely on multi-material deposition or material doping to achieve high refractive index contrast, unlike the biological counterparts that often rely on single-materials through structural variations. In this work, we report single-material polymeric distributed Bragg reflectors fabricated from the infiltration of polylactic acid into 3D anodic aluminium oxide templates. These templates act as sacrificial scaffolds for the nanostructuration of the polymeric material, generating a 3D polymer network with periodic modulations. The obtained structures present very high reflectance, above 95%, with a low number of periods around 20 repeating layers. These structures offer a new approach to the generation of flexible single-material DBRs with high reflectance, an important issue in all-polymer photonic systems.