Highly Enhancing Electrical, Thermal, and Mechanical Properties of Polypropylene/Graphite Intercalation Compound Composites by In Situ Expansion during Melt Mixing

Polypropylene/graphite intercalation compound (PP/GIC) composites are prepared via melt mixing at three different temperatures (180, 200, and 220 °C). The dispersion of GICs in the composites is clearly improved due to the increased interlamellar spacing caused by in situ expansion of GICs at higher temperatures, which facilitates the intercalation of PP molecular chains into the GIC galleries. As a result, the PP/GIC composite with 10 wt% GICs prepared at 220 °C (PG220) presents a dielectric constant of about 1.3 × 108 at 103 Hz, which is about six orders higher than that of the composite prepared at 180 °C (PG180). Moreover, the thermal conductivity of the PG220 sample (0.63 Wm−1K−1) is 61.5% higher than that of the PG180 sample. The well-dispersed GICs accelerates the crystallization of PP by increasing the nucleation point and enhances the thermal stability of the composites. The PG220 sample shows a Young’s modulus that is about 21.2% higher than that of the PG180 samples. The results provide an efficient approach for fabricating polymer/GIC composites without complex exfoliation and dispersion processes.

Infra-Red Active Dirac Plasmon Serie in Potassium Doped-Graphene (KC8) Nanoribbons Array on Al2O3 Substrate

A theoretical formulation of the electromagnetic response in graphene ribbons on dielectric substrate is derived in the framework of the ab initio method. The formulation is applied to calculate the electromagnetic energy absorption in an array of potassium-doped graphene nanoribbons (KC8-NR) deposited on a dielectric Al2O3 substrate. It is demonstrated that the replacement of the flat KC8 by an array of KC8-NR transforms the Drude tail in the absorption spectra into a series of infrared-active Dirac plasmon resonances. It is also shown that the series of Dirac plasmon resonances, when unfolded across the extended Brillouin zones, resembles the Dirac plasmon. The Dirac plasmon resonances’ band structure, within the first Brillouin zone, is calculated. Finally, an excellent agreement between the theoretical absorption and recent experimental results for differential transmission through graphene on an SiO2/Si surface is presented. The theoretically predicted micrometer graphene nanoribbons intercalation compound (GNRIC) in a stage-I-like KC8 is confirmed to be synthesized for Dirac plasmon resonances.

Synthesis of Carbon Nitride Intercalation Compound Composite and Study of Visible Light-Induced Photocatalytic Performance

Novel visible light-induced carbon nitride intercalation compound (CNIC) with iron oxide composite photocatalyst with different content of iron oxide were synthesized through simple mixing and heat treatment. The composite photocatalyst was characterized by Fourier transform infrared (FT-IR) spectroscopy and BET surface area measurements. The photocatalytic oxidation ability of the novel composite photocatalyst was evaluated using methyl range (MO) as a target pollutant. The experimental results showed the composites with a content of iron oxide exhibited the higher photocatalytic activity than either single-phase iron oxide or CNIC under visible-light irradiation. The as-prepared composite photocatalyst exhibits an improved photocatalytic activity due to enhancement of photo-generated electron–hole separations at the interface.

Supramolecular cocrystals built through redox-triggered ion intercalation in π-conjugated polymers

Self-organization in π-conjugated polymers gives rise to a highly ordered lamellar structure, in which inter-chain stacking spontaneously forms two-dimensional conjugated sheets. This multi-layer stacked nature of semicrystalline polymers allows the inclusion of various functional molecules. In particular, redox-triggered ion-intercalation is an ideal system for molecular doping, for which extremely high charge carrier density has been achieved. Here, we conducted a detailed structural analysis and electron density simulation to pinpoint exactly where the guest dopants are located periodically in the void space in a polymer’s lamellae. Our findings are indicative of an intercalation compound of layered polymers and a guest intercalant. We show that a homogeneous cocrystal structure can be realized throughout the host polymer medium, which is proved by the observation of coherent carrier transport. The intercalation cocrystal nature gives the best achievable doping level in semicrystalline polymers and excellent environmental stability. These findings should open up possibilities for tuning the collective dynamics of functional molecules through intercalation phenomena.