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 β-cyclodextrin cross-linking polymer/1-(2-pyridlazo)-2-naphthol (β-CDP-PAN) particles were synthesized. Then the electrorheological properties of the suspensions of β-CDP-PAN particles in silicone oil have been investigated under DC electric fields. It was found that the yield stress of the typical β-CDP-PAN ER fluid was 6.16 KPa in 5 kV/mm, which is much higher than that of pure β-cyclodextrin polymer (β-CDP), that of pure 1-(2-pyridlazo)-2-naphthol (PAN) as well as that of the mixture of the host with the guest (β-CDP+PAN). The structure of β-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 β-CDP. Just as expected, the improvement of dielectric constant, conductivity and loss tangent of β-CDP resulted in good ER effect of β-CDP-PAN. Furthermore, it was found that the cross-linking degree (CLD) of the polymer strongly influences the ER behavior of β-CDP-PAN and β-CDP. When CLD remains in the range of 4-6, β-CDP-PAN exhibits much stronger ER effect, and for β-CDP, its suitable range is 5–8.