Tuning the refractive index of blended polymer films by RIR-MAPLE deposition

Abstract

Graded index polymer films enable novel optics using rigid or flexible substrates, such as waveguides or anti-reflection coatings. Previously, such films have been fabricated by nanoimprint lithography or the decomposition of a single component in polymer blends. Yet, it is desirable to have precise control over the polymer film composition in order to have the most flexibility in designing refractive index profiles. Resonant-infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) is a polymer thin film deposition technique that enables multi-layer structures on a wide variety of substrate materials, regardless of the solubilities of constituent polymers. In this work, the feasibility of tuning the refractive index of blended polymer films of polystyrene and poly(methyl methacrylate) deposited by RIR-MAPLE is demonstrated. Different polymer blend film compositions are deposited using RIR-MAPLE by varying the polymer target ratio. Transmission electron microscopy and atomic force microscopy are used to characterize the film morphology.

Tuning the Refractive Index of Homopolymer Blends by Controlling Nanoscale Domain Size via RIR‐MAPLE Deposition

“…The film surfaces were featureless and began to charge at magnifications less than that of the images of Figure . A TEM image of the RuO 4 ‐stained film, which clearly shows the separate PS and PMMA components of the blend, has been published elsewhere . The SEM images for the 25%, 50%, and 75% porosity films, shown in Figure a–c, respectively, clearly demonstrate that the porosity increases as the PMMA content increases in the blended homopolymer films deposited by RIR‐MAPLE.…”

“…Solution‐cast films of polymer blends often require the employment of diblock copolymers with tailored block sizes or substrate surface treatments that drive homopolymer blending in order to approach an effective medium . In contrast, emulsion‐based resonant infrared matrix‐assisted pulsed laser evaporation (RIR‐MAPLE) is an organic thin‐film deposition technique (variation of pulsed laser deposition) that is capable of creating a polymeric, optical effective medium with a specific RI due to nanoscale domains within the polymer blend. Therefore, this paper demonstrates emulsion‐based RIR‐MAPLE as a technique to enable porous polymer networks with a specified RI that is designed using effective medium theory and is lower than those of the constituent materials in the polymer blend.…”

Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique for deposition of hybrid nanostructures

“…The other way to change the refractive index is introducing nanoscale pores which filled by air into the film. The co-depositing of polystyrene (PS) and PMMA was carried by McCormick et al [54]. After the deposition process, researchers dissolved away the PMMA.…”