|With the emergence of smart electronic devices, we have witnessed a rapid surge in the growth and subsequent drive-in for the miniaturization of electronic interfaces. Any electronic gadget that transmits, distributes, or uses electrical energy creates electromagnetic interference (EMI), has harmful impacts on device performance. This increase in unrestricted EM pollution can also affect human wellbeing as well as the surrounding environment if proper shielding is not provided. Various EM screeners are designed in the last few decades, such as metals and metallic architectures, ferrite pads, ferritic paints and so on. While each one of them efficient in certain terms but also suffers some serious drawbacks such as corrosion, high weight structure, reflection-driven mechanism and so on. Polymer nanocomposites evolved rapidly as one of the promising EM absorbers as they address all the drawbacks of previously mentioned materials. Among the various nanocomposites, Polyvinylidene fluoride (PVDF)-based nanocomposites have been studied for EMI shielding applications involving various kinds of fillers. Heterogeneous dispersion of conducting and magnetic nanoparticles in the polymer matrix leads to synergistic absorption of microwave radiation in these systems. However, materials derived out of these nanocomposites are often encountered with few drawbacks such as high filler loading and large thickness, making them unsuitable for smart, sophisticated and high-end applications. However, the inclusion of only a single component (such as conducting, magnetic, or dielectric) in a polymer matrix to design EM shields failed to provide significant shielding values at smaller thicknesses. However, though satisfactory shielding may be achieved by increasing the filler loading, it may result in processing difficulties and poor structural properties in the case of composites. To address all the discussed, this thesis titled “Polyvinylidene fluoride(PVDF) based nanocomposites with multi-layered architecture containing core-shell nanomaterials for electromagnetic interference shielding” features the systematic studies of key requirement properties to sort out the challenges. This thesis attempts to provide various synthesis and fabrication techniques of core-shell nanomaterials and core-double-shell nanomaterials based polymer nanocomposites for EMI shielding and some other associated applications. This work also provides some physical insight into the materials design and mechanism of shielding at high frequency in polymer composite systems with the proper design choices.
Under this framework, current work discusses few strategies to design and synthesize multicomponent core-shell heterostructures, composited with PVDF to make multi-layered architectures, which have the potential to deliver better shielding values at relatively lower filler loading and low thickness, extremely desired as per state key requirement.
Designed core-shell nanostructures when composited with PVDF matrix, led to maximum attenuation of incoming electromagnetic radiation ‒ a remarkable 42 dB (> 99.99% attenuation) dominated by absorption (82%) for 600-micron thickness. Additionally, these composites were effective in blocking ultraviolet radiation (both UVA and UVB) up to 99.9%. Apart from being an effective shield, these composites were also able to dissipate heat very quickly, were durable at very high service temperatures, and under mechanical stresses.