Abstract
In this study, two types of
highly transparent polyimide–nanocrystalline-titania hybrid optical films with a relatively high titania content were fabricated using the sol-gel process. An organo-soluble polyimide was synthesized from 4,4’-(hexafluoroisopropylidene) diphthalic anhydride, 3,3’-diaminodiphenyl sulfone, and 4-aminobenzoic acid. Such carboxylic acid end groups provided the organic–inorganic bonding with titania and obtained a homogeneous hybr id solution.
The surface hardness and elastic modulus of polyimide and the polyimide–nanocrystalline-titania hybrid films increased from
0.5 to 1.26 GPa and 5.5 to 20.57 GPa, respectively, with respect to an increase in the inorganic content from 0 to 6 0 w t%.
Transmission electron microscopy and X-ray diffraction indicated the formation of nanocrystalline-titania domains of approximately 3-4 nm in the hybrid films. A three layer antireflection coating based on the prepared hybrid films was
designed and posses sed a reflectance of less than 1% in the visible range. The experimental results suggest that the prepared hybrid films demonstrate high thermal stability, favorable surface planarity, tunable refractive indices, and optical transparency in the visible range. These results indicate that the polyimide–nanocrystalline-titania hybrid materials have potential applications for optical devices..
Keywords
Polyimide Titanium butoxide Refractive index Cutoff wave length.
Citation
YANG YEN YU, HUI-HUAN YU, WEN CHEN CHIEN, Synthesis and c haracterization of highly transparent nanocomposite optical films, Optoelectronics and Advanced Materials - Rapid Communications, 11, 3-4, March-April 2017, pp.221-228 (2017).
Submitted at: Aug. 3, 2016
Accepted at: April 6, 2017