Composites of polyvinylchloride (PVC) embedded with different ratios of graphene nano-platelets (GnP) were prepared by the casting method. Some techniques as X-ray diffraction technique (XRD), Fourier transform infrared (FT-IR), optical microscopy, and scanning electron microscopy (SEM) were investigated. The crystalline structure of GnP dominated by increasing its ratio to 2.5 wt.% in the hosting matrix compared to the amorphous structure of the pristine PVC. Microstructural analysis showed uniform distribution of GnP in PVC with some aggregates. Also, the article represents a study of the impact of GnP loading on PVC dielectric parameters such as dielectric loss, electric modulus, ac conductivity, and their dependencies on frequency and temperature. The permittivity ε' displayed an increase in its values with increasing GnP content due to the creation of a strengthened interfacial polarization phenomenon. The values of the activation energy of the polymer were decreased with increasing the content of GnP due to the growing number of conductive networks in the composites. Therefore, GnP enhanced considerably the conductivity of the polymer composites. The mechanical strength of PVC improved with increasing GnP content in which the tensile strength increased up to ∼100%. However, Young’s modulus of PVC enhanced remarkably to be about 109%. In contrast, the elongation at break of PVC decreased by GnP reinforcement from 139.5 to 28.4% by incorporate 0.25% GnP.

The electronic, sensing, and transport properties of doped square hexagonal boron nitride (shBN) quantum dots were investigated using density functional theory calculations. The electronic and magnetic properties were controlled by substitutional doping. For instance, heterodoping with Si and C atoms decreased the energy gap to half its value and converted the insulator shBN quantum dot to a semiconductor. Doping with a single O atom transformed the dot to spin half metal with a tiny spin-up energy gap and a wide spin-down gap. Moreover, doping and vacancies formed low-energy interactive molecular orbitals which were important for boosting sensing properties. The unmodified shBN quantum dot showed moderate physical adsorption of NO₂, acetone, CH₄, and ethanol. This adsorption was elevated by doping due to interactions between electrons in the low-energy orbitals from the doped-shBN dot and π-bond electrons from the gas. The transport properties also showed a significant change in the current by doping. For instance, the spin-up current was very high compared to the spin-down current in the shBN dots doped with an O atom, confirming the formation of spin half metal. The spin-up/down currents were strongly affected by gas adsorption, which can be used as an indicator of the sensing process.