First observation of the confinement effect upon electric field orientation of liquid crystals

02/08/2014

First observation of the confinement effect upon electric field orientation of liquid crystals

Elucidation of confinement effect on the properties of liquid crystals

Summary

A research group led by Professor Kazue Kurihara of the Advanced Institute for Materials Research (AIMR) at Tohoku University found that the orientation of liquid crystal could not be changed by applying the electric field when the distance between two solid surfaces confining the liquid crystal molecules became less than 13 nm. This finding was obtained by the utilization of the resonance shear measurement developed by Prof. Kurihara Tohoku Univ.

Liquid crystal displays are composed of liquid crystal molecules sandwiched between two substrates and they are oriented by the surface anchoring. Images on display can be changed by controlling the orientation of liquid crystal molecules by applying an external electric field. Prof. Kurihara group has developed a resonance shear measurement method (RSM), which measures the resonance response of oscillating unit, and can evaluate the structuring, rheological and tribological properties of confined liquids via the sensitive changes in the amplitude and the frequency of the resonance peak as function of at surface separation distances (D) from μm (bulk liquid region) to nm level thickness (nano-confined liquid region) continuously. Utilizing this method, liquid crystal orientation and responses to electric fields was evaluated as a function of surface separation distance. This study revealed for the first time that once the distance from the surface or distance between the surfaces decreased to a certain value (ca. 17 nm in this study), external influences such as electric fields can no longer control the orientation of the molecules (liquid crystal).

The obtained results can lead to a better understanding of the confinement effect (solid walls limiting the movement of molecules) and can give information about the limits in the miniaturization of liquid crystal displays.

The research results have been published in the online edition of the British scientific journal Soft Matter on February 7, 2014 (GMT). The paper's title is "Effect of confinement on electric field induced orientation of a nematic liquid crystal."

Article Information

S. Nakano, M. Mizukami, K. Kurihara, "Effect of confinement on electric field induced orientation of a nematic liquid crystal." Soft Matter (2014) Abstract(will open in a new tab)

Contact

about research

Professor Kazue Kurihara
Advanced Institute for Materials Research, Tohoku University

TEL : +81-22-217-6152
E-mail : kurihara*tagen.tohoku.ac.jp (Replace * with @)

Public Relations

Yasufumi Nakamichi
Advanced Institute for Materials Research, Tohoku University

TEL : +81-22-217-6146
E-mail : outreach*wpi-aimr.tohoku.ac.jp (Replace * with @)