Dielectric relaxation of liquid-crystalline polyrotaxane

¹  Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8561, Japan
²  CREST, Japan Science and Technology Agency (JST) - 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
³  Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology - Koganei, Tokyo 184-8588, Japan

Received: 12 April 2007
Accepted: 1 August 2007

Abstract

A new supramolecular system, liquid-crystalline polyrotaxane (LCPR), has been recently prepared by introduction of 4-cyano--n-pentylbiphenyl (5CB) groups to the cyclic molecules of a polyrotaxane (PR) consisting of polyethylene glycol (PEG) and α-cyclodextrin (α-CD). Here we measured and compared the dielectric relaxations of PR and LCPR in solid state to investigate molecular motions of α-CD in PR and LCPR. It was found that PR exhibited a single relaxation mode while LCPR had two modes. These results suggested that the relaxation mode in PR would be due to the sliding fluctuation of α-CD along the axis chain and that the other mode in LCPR should arise from the rotational fluctuation of α-CD modified by 5CB.