In Situ Polymerization of Chiral Poly(fluorene-alt-benzothiadiazole) Nanocomposites with Enhanced Chirality

Hongsub Jee,Jaehyeong Lee,Hyeong-Sub Oh

doi:10.3390/app10238740

Hongsub Jee, Jaehyeong Lee + Show 1 more

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https://doi.org/10.3390/app10238740

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Abstract

Poly(fluorene-alt-benzothiadiazole) (PFBT) is a promising chiral polymer for use in metamaterials and other photonic applications, due to its large chiral optical activity at visible wavelengths. However, its usages are very limited, since it is not readily patternable into microstructures and challenging to apply to applications. In this paper, we demonstrate photo patterning of chiral PFBT/Achiral SU-8 photoresist to produce high quality structures while retaining the extraordinary chiral optical activity of our previously-reported PFBT/SU8 nanocomposite films. The ability to produce cleanly patterned microfeatures with high chirality may enable wider use of PFBT in chiral metamaterials and other photonic applications.

Highlights

The research field of chiral photonics is an area of growing interest, with potential to contribute to applications ranging from negative- and near-zero refractive index metamaterials [1,2], to chiral bioimaging [3,4], to all-optical switching [5,6,7,8]
We have previously demonstrated the plasmonic enhancement of chirality in PFBT films using gold nanoparticles [25], and more recently, we reported on thin film fabrication of nanocomposites of a PFBT in a photopolymer matrix [26]
We demonstrate the fabrication of cleanly-patterned PFBT/SU-8 nanocomposite structures that still exhibit dramatically enhanced optical activity compared with pure PFBT film, even in the absence of a residual film of chiral nano-aggregates between the patterned structures

Summary

Introduction

The research field of chiral photonics is an area of growing interest, with potential to contribute to applications ranging from negative- and near-zero refractive index metamaterials [1,2], to chiral bioimaging [3,4], to all-optical switching [5,6,7,8] Realization of such applications, and the full potential of this field, demands materials with dramatically greater optical chirality than that observed in naturally occurring materials [9,10,11]. Conventional photolithography can be used to produce patterns in this material with sharp edges and no residual material between patterned features This adds a valuable new tool to the palette of materials and processes available for pursuing chiral photonics

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