Near-surface alignment of polymers in rubbed films

ABSTRACT RUBBED polymer films (generally polyimides) are used in flat-panel displays to control the alignment of liquid crystals in contact with the polymer1–8, a phenomenon first discovered

by Maugin1 in 1911. Buffing the film with a cloth produces liquid-crystal alignment in the rubbing direction. Several mechanisms have been proposed to explain this effect. The generation of

microgrooves or scratches on the polymer surface during rubbing has led to the suggestion that alignment is the result of long-range elastic effects induced by these surface features3–5.

Others have suggested that the polymer chains near the surface are aligned during rubbing and that these then serve as templates for liquid-crystal alignment6–13. Other studies 10–l2 have

implied that both mechanisms might be operative. Here we present X-ray scattering measurements which show unambiguously that rubbing a polyimide film causes near-surface alignment of the

polymer molecules. For a film 200 nm thick, most of the polymer chains within a thin surface region (about 5 nm thick) are aligned in the rubbing direction; for a 6-nm film essentially all

of the chains are aligned within 20° of the rubbing direction. This marked orientation of the near-surface chains at temperatures far below the bulk glass transition temperature shows that

the mechanical properties of the near-surface region differ significantly from those of the bulk polymer. Access through your institution Buy or subscribe This is a preview of subscription

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ACCESS OPTIONS: * Log in * Learn about institutional subscriptions * Read our FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS MOBILITY GRADIENTS YIELD RUBBERY SURFACES

ON TOP OF POLYMER GLASSES Article 18 August 2021 MORPHOLOGIES OF POLYMER CHAINS SPUN ONTO SOLID SUBSTRATES Article 25 July 2024 ROLL-TO-PLATE 0.1-SECOND SHEAR-ROLLING PROCESS AT ELEVATED

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Kyushu University, Fukuoka, Japan * Michael F. Toney, Thomas P. Russell, J. Anthony Logan and Hirotsugu Kikuchi: Almaden Research Center, IBM Research Division, 650 Harry Road, San Jose,

California 95120, USA * James M. Sands and Sanat K. Kumar: Department of Materials Science and Engineering, AUTHORS AND AFFILIATIONS * The Pennsylvania State University, University Park,

Pennsylvania, 16802, USA Michael F. Toney, Thomas P. Russell, J. Anthony Logan, Hirotsugu Kikuchi, James M. Sands & Sanat K. Kumar Authors * Michael F. Toney View author publications You

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author publications You can also search for this author inPubMed Google Scholar * Hirotsugu Kikuchi View author publications You can also search for this author inPubMed Google Scholar *

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Google Scholar RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Toney, M., Russell, T., Logan, J. _et al._ Near-surface alignment of polymers in rubbed

films. _Nature_ 374, 709–711 (1995). https://doi.org/10.1038/374709a0 Download citation * Received: 24 October 1994 * Accepted: 07 March 1995 * Issue Date: 20 April 1995 * DOI:

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