Correlation between rub-induced grooves in a polyimide-treated substrate and microstructure of rubbing fiber: An atomic force microscopy study

Mahajan, Milind P.; Rosenblatt, Charles

doi:10.1063/1.367883

Cited by 39 publications

(19 citation statements)

References 18 publications

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“…[3][4][5][6][7] Although successfully applied for the past 30 years for the production of liquid crystal displays, the mechanism of the alignment of LC molecules on such a rubbed substrate is not precisely understood. According to the elastic continuum theory of Berreman 8 the rubbing induces grooves on the polymer surface and the liquid crystal molecules prefer to align parallel to the direction of the grooves.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of liquid crystal alignment on submicron patterned surfaces

Rastegar

Škarabot

Blij

et al. 2001

Journal of Applied Physics

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The alignment mechanism of liquid crystals on polymeric surfaces that were patterned using an atomic force microscope ͑AFM͒ tip was studied by polarizing optical microscopy. Depending on the thickness of the polymer, polymer chain alignment or grooves appear to be responsible for the liquid crystal alignment. In thick polymer films ͑above 100 nm͒ the polymer chains will align in the direction of the scan due to the large lateral force exerted by the tip. In thin polymer films ͑5-20 nm͒ the polymer chains are strongly fixed to the surface and will not realign by the tip; instead grooves will be formed. The azimuthal surface anchoring the energy of thick polymer films does not depend on the scan line separation and scan force, is of the same order of magnitude as for conventionally rubbed polyimide surfaces, but increases by the number of scans. AFM patterned pixels do not show a pretilt angle.

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Section: Introductionmentioning

confidence: 99%

Mechanism of liquid crystal alignment on submicron patterned surfaces

Rastegar

Škarabot

Blij

et al. 2001

Journal of Applied Physics

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“…However, LC alignment is still based on the rubbing of polyimide (PI). The traditional rubbing process for LC alignment has major limitations such as debris and electrostatic discharge, which produce local defects and streaks and result in the degradation of the display resolution [1][2][3][4][5][6]. Over the past several years, there have been a number of challenges to replace PI based rubbing process by nonrubbing methods from methods from traditional oblique deposition, the UV exposure to up-to-data u rubbing, the nanoimprint lithography, and the nanostructured alignment method, which provides controllabililty, nonstop process, and high resolution display, has been intensively investigated with inorganic materials so far.…”

Section: Introductionmentioning

confidence: 99%

Liquid Crystal Alignment Capabilities on SiNx Thin Films Via Ion-Beam Irradiation

Kim

Park

et al. 2010

Ferroelectrics

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The aligned liquid crystals (LCs) display on SiNx thin films using ion-beam (IB) irradiation was studied with controllability of pretilt angle depending on incident energies of the IB. The LCs alignment property for the SiNx thin films were observed to verify the practical application potential. A good LCs alignment of vertical alignment LCs cells on SiNx thin film surfaces irradiated with incident IB energy of 1800 eV was achieved.The atomic force microscopy (AFM) images of LCs on SiNx thin film surfaces irradiated with IB energy was used for the surface analysis.

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“…The polyimide surfaces with clothes produced an anisotropic orientation of PI films to the rubbing direction [1][2][3][4][5]. Rubbing of alignment layers is widely used in the industrial process.…”

Section: Introductionmentioning

confidence: 99%

Photo-alignment using a Photo-decomposition Polyimide and Effect of Reactive Monomers

Kim¹,

Yi²,

Shin³

2012

Molecular Crystals and Liquid Crystals

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Photoreactivity of photo-decomposible polyimde was studied with and without reactive monomer, RM257. Recently photo reactive monomers have been draw attention for better alignment of liquid crystals and broad viewing angle. Interfacial effects as well as macro molecular interaction have been studied to enhance anchoring energy of liquid crystal. After irradiation, polyimide film gives LC alignment, perpendicular to polarization direction of the UV irradiation. LC aligning direction is measured by polar diagram. We had time to adjust during 10min-30 min. And we exposed to linearly polarized UV the angle vertically or horizontally by measured the degree of LC alignment. And we used 253.7 nm UV light by the use of band pass filter. Because this photo-decomposition polyimide film when using the 253.7 nm UV light is active in the reaction.We are the best time of the photo-alignment can be found by dichroic ratio [= (A per -A para )/(A per + A para )]. Normal photo-decomposition polyimide films were 0.584 dichroic ratio at 15 min and Reactive monomer added photo-decomposition polyimide films were 0.623 dichroic ratio at 10 min.Photo-decomposible polyimide reacts very efficiently with UV light. We have studied photo-alignment with CBDA-DAPM-DA polyimide by irradiating with 253.7 nm UV light. The polarization direction of liquid crystals were perpendicular to the polarization of incident light with and without reactive monomer(RM). The dichroic ratio obtained from the liquid crystal cells assembled with photo-irradiated alignment layer were 0.584 for the 15 min irradiated of UV light without reactive monomer. The dichroic ratio became 0.623 with 10 min irradiated polyimide film with RM.

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Correlation between rub-induced grooves in a polyimide-treated substrate and microstructure of rubbing fiber: An atomic force microscopy study

Cited by 39 publications

References 18 publications

Mechanism of liquid crystal alignment on submicron patterned surfaces

Mechanism of liquid crystal alignment on submicron patterned surfaces

Liquid Crystal Alignment Capabilities on SiNx Thin Films Via Ion-Beam Irradiation

Photo-alignment using a Photo-decomposition Polyimide and Effect of Reactive Monomers

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