In this paper, ZnO nanowires and ZnO nanotrees have been prepared and their microwave absorption properties have been investigated in detail. Complex permittivity and permeability of the ZnO nanostructures and paraffin composites have been measured in a frequency of 0.1–18 GHz. Excellent microwave absorption performances have been observed in ZnO nanotree composite compared to ZnO nanowire composite, and the maximum absorption is enhanced as the concentration of the nanotrees increases in the composite. The value of minimum reflection loss for the composites with 60 vol % ZnO nanotrees is −58 dB at 4.2 GHz with a thickness of 4.0 mm. Such strong absorption is attributed to the unique isotropic antenna morphology of the ZnO nanotrees in the composite.

Block copolymers represent a potentially new class of materials for integrated optics. Before these materials can be used as optical waveguide materials, however, their optical waveguiding properties need to be well understood. In this paper, lamellar-forming block copolymer waveguides are treated and modeled as ideal multilayer structures in which the lamellae are oriented parallel to the substrate and superstrate interfaces. A computer program based on an N-layer waveguide formalism is used to calculate the propagation constants and plot the optical field intensity distributions of some sample diblock and triblock copolymer thin-film waveguides. In a block copolymer thin film, individual block copolymer domains can have anisotropic optical properties due to chain stretching, in the case of coil-coil block copolymers, or due to the presence of a liquid crystalline block, in the case of rod-coil block copolymers.As a result, optical anisotropy of the layers is also treated in the waveguide formalism. Theoretical waveguide calculations show that block copolymer films with a domain size smaller than about A/5 behave optically like homogeneous uniaxial films. Consequently, block copolymers represent a convenient way of making waveguides with a controlled birefringence. In contrast, block copolymer films with a domain size larger than about U3 but less than the wavelength of light are found to preferentially segregate the light into the high refractive index domains. When the low-index layer is at the air interface, only the high-order modes are supported and a greater segregation of the light can be achieved. ABC triblock copolymer films, in which the refractive index of the B and C blocks is larger than that of the A block, are found to exhibit even better confinement of the light into the high-index regions. The optical waveguiding properties predicted for large domain size block copolymers are not seen in single slab homopolymer waveguides and may have potential device applications.