Effects of prestrain applied to poly(ethylene terephthalate) substrate on microstructures and morphologies of porous TiO2 film and optical scattering behaviors of light

Tse Chang Li, Cheng Fang Ho, Jen Fin Lin

Research output: Contribution to journalArticle

Abstract

A mold was designed to simulate a thin ceramic film coating on a soft, flexible substrate using a rotating deposition system. With this mold, three prestrains (2%, 4%, and 6%) were applied to a polyethylene terephthalate (PET) substrate before the deposition of a thin TiO2 film. The contact angle of the substrate and, thus, the mean TiO2 particle size were affected by the prestrain. The effects of the mean particle size of TiO2 on the surface roughness and cavity area ratio of the porous film and on the scattering behavior of light were investigated. A goniophotometer and Advanced System Analysis Program were employed for the light analyses of bidirectional scatter distribution functions and their calibration. A spectrometer with an integrating sphere was applied to determine the total scatters (TSs) of transmittance and reflection. An increase in the prestrain increased the mean particle size of TiO2 deposited on the substrate and, thus, the mean surface roughness, cavity/void depth, and cavity area ratio. PET/TiO2 specimens with various prestrains were prepared that satisfy the Harvey-like model but without the isotropic, diffusive property in scatter. The bidirectional transmittance distribution function area and TS-transmittance results are governed by the mean particle size and, thus, the cavity/void geometries and surface roughness. These values decrease with increasing PET prestrain. The bidirectional reflection distribution function area and TS-reflection, however, are governed by the adsorbed carbon and its absorption thickness. These values increase with increasing C1s peak value in x-ray photoelectron spectroscopy spectra.

Original languageEnglish
Pages (from-to)816-827
Number of pages12
JournalApplied optics
Volume54
Issue number4
DOIs
Publication statusPublished - 2015 Jan 1

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Engineering (miscellaneous)
  • Electrical and Electronic Engineering

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