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Specular and diffuse reflectance of phase-separated polymer blend films

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Abstract
Diffuse reflectors have various applications in devices ranging from liquid crystal displays to light emitting diodes, to coatings. Herein, specular and diffuse reflectance from controlled phase separation of polymer blend films, a well-known self-organization process, are studied. Temperature-induced spinodal phase separation of polymer blend films in which one of the components is selectively extracted is shown to exhibit enhanced surface roughness as compared to unextracted films, leading to a notable increase of diffuse reflectance. Diffuse reflectance of UV-visible light from such selectively leached phase-separated blend films is determined by a synergy of varying lateral scale of phase separation (approximate to 200 nm to 1 mu m) and blend film surface roughness (0-40 nm). These critical parameters are controlled by tuning annealing time (0.5-3 h) and temperature (140, 150, 160 degrees C) of phase separation. Angle-resolved diffuse reflection studies show that the surface-roughened polymer films exhibit diffuse reflectance up to 40 degrees from normal incident light in contrast to optically uniform as-cast films that exhibit largely specular reflectance. Furthermore, the intensity of the diffusively reflected light can be enhanced (300-700 nm) or reduced (220-300 nm) significantly by coating the leached phase-separated films with a thin silver over layer.
Keywords
diffuse reflectance, optics, phase separation, polymer blends, surface roughening, BUTTERFLY WING SCALES, LIGHT-EMITTING DIODE, POLY(METHYL METHACRYLATE), SPINODAL DECOMPOSITION, PHOTONIC CRYSTALS, POLYSTYRENE, EXTRACTION, MORPHOLOGY, SURFACES, REFLECTIVITY

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MLA
Nallapaneni, Asritha, Matthew Shawkey, and Alamgir Karim. “Specular and Diffuse Reflectance of Phase-separated Polymer Blend Films.” MACROMOLECULAR RAPID COMMUNICATIONS 38.12 (2017): n. pag. Print.
APA
Nallapaneni, A., Shawkey, M., & Karim, A. (2017). Specular and diffuse reflectance of phase-separated polymer blend films. MACROMOLECULAR RAPID COMMUNICATIONS, 38(12).
Chicago author-date
Nallapaneni, Asritha, Matthew Shawkey, and Alamgir Karim. 2017. “Specular and Diffuse Reflectance of Phase-separated Polymer Blend Films.” Macromolecular Rapid Communications 38 (12).
Chicago author-date (all authors)
Nallapaneni, Asritha, Matthew Shawkey, and Alamgir Karim. 2017. “Specular and Diffuse Reflectance of Phase-separated Polymer Blend Films.” Macromolecular Rapid Communications 38 (12).
Vancouver
1.
Nallapaneni A, Shawkey M, Karim A. Specular and diffuse reflectance of phase-separated polymer blend films. MACROMOLECULAR RAPID COMMUNICATIONS. 2017;38(12).
IEEE
[1]
A. Nallapaneni, M. Shawkey, and A. Karim, “Specular and diffuse reflectance of phase-separated polymer blend films,” MACROMOLECULAR RAPID COMMUNICATIONS, vol. 38, no. 12, 2017.
@article{8550532,
  abstract     = {Diffuse reflectors have various applications in devices ranging from liquid crystal displays to light emitting diodes, to coatings. Herein, specular and diffuse reflectance from controlled phase separation of polymer blend films, a well-known self-organization process, are studied. Temperature-induced spinodal phase separation of polymer blend films in which one of the components is selectively extracted is shown to exhibit enhanced surface roughness as compared to unextracted films, leading to a notable increase of diffuse reflectance. Diffuse reflectance of UV-visible light from such selectively leached phase-separated blend films is determined by a synergy of varying lateral scale of phase separation (approximate to 200 nm to 1 mu m) and blend film surface roughness (0-40 nm). These critical parameters are controlled by tuning annealing time (0.5-3 h) and temperature (140, 150, 160 degrees C) of phase separation. Angle-resolved diffuse reflection studies show that the surface-roughened polymer films exhibit diffuse reflectance up to 40 degrees from normal incident light in contrast to optically uniform as-cast films that exhibit largely specular reflectance. Furthermore, the intensity of the diffusively reflected light can be enhanced (300-700 nm) or reduced (220-300 nm) significantly by coating the leached phase-separated films with a thin silver over layer.},
  articleno    = {1600803},
  author       = {Nallapaneni, Asritha and Shawkey, Matthew and Karim, Alamgir},
  issn         = {1022-1336},
  journal      = {MACROMOLECULAR RAPID COMMUNICATIONS},
  keywords     = {diffuse reflectance,optics,phase separation,polymer blends,surface roughening,BUTTERFLY WING SCALES,LIGHT-EMITTING DIODE,POLY(METHYL METHACRYLATE),SPINODAL DECOMPOSITION,PHOTONIC CRYSTALS,POLYSTYRENE,EXTRACTION,MORPHOLOGY,SURFACES,REFLECTIVITY},
  language     = {eng},
  number       = {12},
  pages        = {8},
  title        = {Specular and diffuse reflectance of phase-separated polymer blend films},
  url          = {http://dx.doi.org/10.1002/marc.201600803},
  volume       = {38},
  year         = {2017},
}

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