Thin flexible double‐layer microwave absorbers have been fabricated based on polypyrrole (PP)/natural rubber (NR) nanocomposites and their reflection loss characteristics were studied in the range of 8–18 GHz. The PP‐NR matrix was prepared from PP and NR in the ratio of 15:85. The polymers used in this work not only serve as the matrix but also improve the microwave absorption properties. The first layer or impedance matching layer which is comprised of graphite, Fe3O4, and TiO2 nanoparticles in PP‐NR transmits the electromagnetic (EM) wave without reflection. The second layer which is made up of PP‐NR filled with Fe3O4 disperses the EM wave energy. The design of a double‐layer nanocomposite is a method to match the wave impedance, enhance wave absorption ability, and broaden the absorption frequencies. In order to achieve high absorption properties, the EM parameters such as permittivity, permeability, and thickness were controlled precisely according to quarter‐wave plate. The morphology, absorption properties, scattering parameters, thermal and wetting characteristics of double‐layer nanocomposites were investigated. The minimum reflection loss (RL) was −32 dB at 12.1 GHz and the absorbing bandwidth in which the RL < −10 dB was 9 GHz for optimum specimen with 2 mm thickness. For this specimen, the contact angle was equal to 118.7° with water as the liquid. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46565.

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The ongoing emergence of antibiotic‐resistant bacteria has become one of the biggest threats to global health and development today. Pseudomonas aeruginosa and methicillin‐resistant Staphylococcus aureus (MRSA) are important antibiotic‐resistant bacteria due to their increasing resistance to a broad array of antimicrobial agents. Herein, we developed a novel antibacterial nanocomposite based on chitosan and liquid silicone rubber filled zeolite‐A, Ag, and Cu nanoparticles with remarkable antibacterial activity against P. aeruginosa and MRSA. The antibacterial activity of the nanocomposite was studied by disc diffusion and broth culture methods. Besides, the mechanical properties, wetting behavior, and chemical structure of the present nanocomposite were also investigated. The results exhibited that the inhibition zone diameter of the nanocomposite for P. aeruginosa and MRSA were 40 and 27 mm, respectively. It also took approximately 1 h to inhibit the growth of the tested bacteria. The nanocomposite sample with a thickness of around 1 mm showed an elastic elongation of nearly 49% and a contact angle of roughly 120°. Thus, the present nanocomposite was found to be useful in killing and inhibiting the growth of P. aeruginosa and MRSA, and it could also be qualified as a superior elastic and hydrophobic material.

The genotoxic effect of microwave radiation on humans is one of the leading causes of some diseases like cancer. Despite many reported materials for microwave absorption, there is still a demand for a super‐thin and flexible microwave absorber. In the present work, we synthesized Fe3O4/graphene/polyaniline/nitrile butadiene rubber composites with a thickness of 0.7 mm using a melt mixing method. Then, we comprehensively studied the electromagnetic and microwave absorption properties of the composites from 8 to 12 GHz. The composite with 38 wt% Fe3O4 and 6 wt% graphene exhibited the highest microwave absorption of more than 8 dB in the entire range of 8–12 GHz, with a minimum reflection loss of −14 dB at 10.3 GHz. By increasing the weight content of Fe3O4 and graphene, the imaginary part of dielectric permeability and magnetic permeability initially went up and then declined, resulting in poor impedance matching. Hence, we precisely controlled the weight content of the fillers to reach the highest impedance matching and attenuation constant. Consequently, this work opened up a unique way for developing super‐thin, lightweight, flexible microwave‐absorbing materials.