Transition from Spin Dewetting to continuous film in spin coating of Liquid Crystal 5CB

Abstract Spin dewetting refers to spontaneous rupture of the dispensed solution layer during spin coating, resulting in isolated but periodic, regular sized domains of the solute and is pre-dominant when the solute concentration (C n ) is very low. In this article we report how the morphology of liq...

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Autores principales: Palash Dhara, Nandini Bhandaru, Anuja Das, Rabibrata Mukherjee
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Publicado: Nature Portfolio 2018
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spelling oai:doaj.org-article:591c61dbe2f34863bd5dfba47ca491962021-12-02T12:32:21ZTransition from Spin Dewetting to continuous film in spin coating of Liquid Crystal 5CB10.1038/s41598-018-25504-72045-2322https://doaj.org/article/591c61dbe2f34863bd5dfba47ca491962018-05-01T00:00:00Zhttps://doi.org/10.1038/s41598-018-25504-7https://doaj.org/toc/2045-2322Abstract Spin dewetting refers to spontaneous rupture of the dispensed solution layer during spin coating, resulting in isolated but periodic, regular sized domains of the solute and is pre-dominant when the solute concentration (C n ) is very low. In this article we report how the morphology of liquid crystal (LC) 5CB thin films coated on flat and patterned PMMA substrate transform from spin dewetted droplets to continuous films with increase in C n . We further show that within the spin dewetted regime, with gradual increase in the solute concentration, periodicity of the isotropic droplets (λ D ) as well as their mean diameter (d D ), gradually decreases, till the film becomes continuous at a critical concentration (C n *). Interestingly, the trend that λ D reduces with increase in C n is exact opposite to what is observed in thermal/solvent vapor induced dewetting of a thin film. The spin dewetted droplets exhibit transient Radial texture, in contrast to Schlieren texture observed in elongated threads and continuous films of 5CB, which remains in the Nematic phase at room temperature. Finally we show that by casting the film on a grating patterned substrate it becomes possible to align the spin dewetted droplets along the contours substrate patterns.Palash DharaNandini BhandaruAnuja DasRabibrata MukherjeeNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 8, Iss 1, Pp 1-9 (2018)
institution DOAJ
collection DOAJ
language EN
topic Medicine
R
Science
Q
spellingShingle Medicine
R
Science
Q
Palash Dhara
Nandini Bhandaru
Anuja Das
Rabibrata Mukherjee
Transition from Spin Dewetting to continuous film in spin coating of Liquid Crystal 5CB
description Abstract Spin dewetting refers to spontaneous rupture of the dispensed solution layer during spin coating, resulting in isolated but periodic, regular sized domains of the solute and is pre-dominant when the solute concentration (C n ) is very low. In this article we report how the morphology of liquid crystal (LC) 5CB thin films coated on flat and patterned PMMA substrate transform from spin dewetted droplets to continuous films with increase in C n . We further show that within the spin dewetted regime, with gradual increase in the solute concentration, periodicity of the isotropic droplets (λ D ) as well as their mean diameter (d D ), gradually decreases, till the film becomes continuous at a critical concentration (C n *). Interestingly, the trend that λ D reduces with increase in C n is exact opposite to what is observed in thermal/solvent vapor induced dewetting of a thin film. The spin dewetted droplets exhibit transient Radial texture, in contrast to Schlieren texture observed in elongated threads and continuous films of 5CB, which remains in the Nematic phase at room temperature. Finally we show that by casting the film on a grating patterned substrate it becomes possible to align the spin dewetted droplets along the contours substrate patterns.
format article
author Palash Dhara
Nandini Bhandaru
Anuja Das
Rabibrata Mukherjee
author_facet Palash Dhara
Nandini Bhandaru
Anuja Das
Rabibrata Mukherjee
author_sort Palash Dhara
title Transition from Spin Dewetting to continuous film in spin coating of Liquid Crystal 5CB
title_short Transition from Spin Dewetting to continuous film in spin coating of Liquid Crystal 5CB
title_full Transition from Spin Dewetting to continuous film in spin coating of Liquid Crystal 5CB
title_fullStr Transition from Spin Dewetting to continuous film in spin coating of Liquid Crystal 5CB
title_full_unstemmed Transition from Spin Dewetting to continuous film in spin coating of Liquid Crystal 5CB
title_sort transition from spin dewetting to continuous film in spin coating of liquid crystal 5cb
publisher Nature Portfolio
publishDate 2018
url https://doaj.org/article/591c61dbe2f34863bd5dfba47ca49196
work_keys_str_mv AT palashdhara transitionfromspindewettingtocontinuousfilminspincoatingofliquidcrystal5cb
AT nandinibhandaru transitionfromspindewettingtocontinuousfilminspincoatingofliquidcrystal5cb
AT anujadas transitionfromspindewettingtocontinuousfilminspincoatingofliquidcrystal5cb
AT rabibratamukherjee transitionfromspindewettingtocontinuousfilminspincoatingofliquidcrystal5cb
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