Enhancing electrorheological behaviors with formation of β-cyclodextrin supramolecular complex

According to the point that the host structure and the properties can be easily modified by the formation of host-guest complex, the supramolecular complexes of beta-cyclodextrin cross-linking polymer/1-(2-pyridlazo)-2-naphthol (beta-CDP-PAN) particles were synthesized. Then the electrorheological properties of the suspensions of beta-CDP-PAN particles in silicone oil have been investigated under DC electric fields. It was found that the yield stress of the typical beta-CDP-PAN ER fluid was 6.16 KPa in 5 kV/mm, which is much higher than that of pure beta-cyclodextrin polymer (beta-CDP), that of pure 1-(2-pyridlazo)-2-naphthol (PAN) as well as that of the mixture of the host with the guest (beta-CDP + PAN). The structure of beta-CDP-PAN was characterized by the fluorescence analysis and IR spectrometry, respectively. The results confirmed that the naphthalene ring of PAN is included in the cavity of beta-CDP. Just as expected, the improvement of dielectric constant, conductivity and loss tangent of beta-CDP resulted in good ER effect of beta-CDP-PAN. Furthermore, it was found that the cross-linking degree (CLD) of the polymer strongly influences the ER behavior of beta-CDP-PAN and beta-CDP. When CLD remains in the range of 4-6, beta-CDP-PAN exhibits much stronger ER effect, and for beta-CDP, its suitable range is 5-8. (C) 2003 Elsevier Science Ltd. All rights reserved.