According to the chemical design, electrorheological properties of supramolecular complex from b-cyclodextrin polymer (b -CDP) were discussed. Six supramolecular complexes of -cyclodextrin polymer with substituted salicylic acid and 3-hydroxy-2-naphthoic acid were syn-thesized by the solid-phase self-assembly method, and their component and structure were characterized by NMR, FT-IR, UV-vis and the fluorescence analysis. Then the electrorheological properties of their suspensions in silicone oil were investigated under DC electric fields. It was found that the yield stresses of these supramolecular complex ER fluids were 7.3—9.8 kPa at 4 kV/mm in DC electric field, which were enhanced by 34%—72% compared with that of pure b-CDP. Among them, that of b-CDP/3-hydroxy-2-naphthoic acid ER fluid was the highest. It was also found that the ER effect of supramolecular complexes can be controlled by changing dif-ferent guests. When the substituted group is at phenyl ring, ER behavior can be slightly adjusted by the different substituted groups, their number as well as their position at phenyl ring. This can be proved by the measurement of dielectric properties.
According to the physical and chemical design, a kind of kaolinite /dimethylsulfoxide/carboxymethyl starch (CMS) ternary nanocomposite was prepared by the two-step composite method. Firstly, the polar liquid-dimethylsulfoxide (DMSO) was directly intercalated into the interlayer of kaolinite, and then the intercalated complex was composite with CMS by the solution method. The results showed that DMSO moderately intercalated the interlayer of kaolinite and the basal spacing of kaolinite was swollen from 0.715 to 1.120 nm. Under the electric fields of 5 kV mm-1 and volume fraction 30%, the static shear stress of kaolinite/DMSO/CMS ternary ERF could reach 17 kPa, which was 14 times and 4.25 times higher than that of pure kaolinite ERF and kaolinite/CMS ERF respectively. At the suitable component ratio (kaolinite:DMSO:CMS=1:0.75:0.6) of nanocomposite, a stronger synergetic effect and the optimum electrorheological effect could be attained. The ternary nanocomposite ERF also had good temperature effect and sedimentation properties. The sedimentation part of ternary nanocomposite ERF was only 9% after 30 days. The results of dielectric properties showed that the dielectric constant and conductivity of ternary nanocomposite ERF had been improved more enormously than that of the single component ERF and binary composite ERF. So the polarization and dielectric mismatch were strengthened, which was suitable to the enhancement of ER effect.
We demonstrated a two-dimensional quasi-crystal dendritic structure model with negative permeability.The microwave transmission and reflection properties of periodic and quasi-crystal dendritic structure mediums with varied angle incidence were measured.The results showed that the resonant peaks of quasi-crystal negative permeability samples and left-handed samples had tiny shift with the altering of incident angle.Because of the influence of coupling between quasi-crystal dendritic cells,the resonance of the entire material was enhanced or weakened.The quasi-crystal dendritic structure model will provide an easy method to design isotropic left-handed materials(LHMs).
It has been shown that optical activity can occur in microemulsion under external electric field and rotation angle can also be tuned by the electric field. A set of microemulsions (water/Span80/transformer oil) with different water concentration were prepared and their optical activity was measured with the changes of applied electric field and θ, the angle between the electric vector of the incident linearly polarized light and the external electric field, using an automatic polarimeter. The experiments indicate that when none of the external electric field, water concentration and θ are zero, there is optical activity in microemulsions. For a given concentration, rotation angle ψ increases with electric field, and it firstly increases, passes through a maximum at C = C0,then monotonically decreases as C increases when electric field keeps constant. The relationship between the rotation angle and θ is also obtained. It is thought that the electric field-induced destroy of spatial symmetry of microemulsion is responsible for the optical activity of microemulsion.
We experimentally investigated the reflection and phase of the left-handed metamaterials (LHMs) in a rectangular waveguide for the normally incident microwave. The samples are constructed by periodically arraying the copper split ring resonators (SRRs) and wires. It is found that for the LHMs with one-layered SRRs, a reflection peak with a depth of -3.3 dB (i.e. with the reflectivity of 47%) occurs in the left-handed range. The dependence of reflection phase on the frequency is different from that of the transmission phase, and the reflection phase has an inflexion at the reflection peaks. For the LHMs with three-layered SRRs, the depth of reflection peak increases with the row number, i.e. reflection is weakened, and the reflection peak has a shift with respect to the left-handed transmission peak. It is thought that the interaction between different layers of SRRs is the reason of the shift.
