Duy Khoe Dinh

Liquid metal (LM) with notable thermal conductivity might be a promising candidate for the thermal management of CPU and GPU used for AI since conventional polymer-based thermal interface materials are not sufficient to dissipate the heat produced by these advanced chips. However, it also has disadvantages, such as leakage, surface-spreading concerns, and processability difficulties due to their inherent high surface tension. The proposed solution to mitigate these issues might be metallic particle incorporation with LM, but the incorporation of those metal particles in general causes the intermetallic reactions resulting the deteriorated thermal performance and processibility. Here, we suggest a facile and straightforward scheme using a mixture of boron nitride nanotubes (BNNT) with LM, while in-situ decoration of Sn (tin) nanoparticles onto the surface of BNNT (BNNT-Sn) through reduction reaction and electrostatic attraction improves its dispersion and wettability in the LM matrix. We report for the first time the BNNT-Sn achieves superior phonon conduction pathways through the nanotubes by increasing the thermal conductivity as high as 30%, and more importantly, the wettability and processibility properties were also enhanced by increasing the viscosity to 180,500 ± 750 mPas from 2,400 mPas for neat LM with just 1.0 wt% of BNNT-Sn assimilation, with an improved rigidity evading leakage and adhesion as well. These improvements can be correlated with the intrinsic attributes of BNNT, such as an optimal aspect ratio and inherent thermal conductivity that contributed to the improvement of viscosity and thermal conduction.

Highly selective etching of silicon nitride (Si₃N₄) and silicon dioxide (SiO₂) has received considerable attention from the semiconductor community owing to its precise patterning and cost efficiency. We investigated the etching selectivity of Si₃N₄ and SiO₂ in an NF₃/O₂ radio-frequency glow discharge. The etch rate linearly depended on the source and bias powers, whereas the etch selectivity was affected by the power and ratio of the gas mixture. We found that the selectivity can be controlled by lowering the power with a suitable gas ratio, which affects the surface reaction during the etching process. X-ray photoelectron spectroscopy of the Si₃N₄ and QMS measurements support the effect of surface reaction on the selectivity change by surface oxidation and nitrogen reduction with the increasing flow of O₂. We suggest that the creation of SiO_xN_y bonds on the surface by NO oxidation is the key mechanism to change the etch selectivity of Si₃N₄ over SiO₂.

As one of the emerging nanomaterials, boron nitride nanotubes (BNNTs) provide promising opportunities for diverse applications due to their unique properties, such as high thermal conductivity, immense inertness, and high-temperature durability, while the instability of BNNTs due to their high surface induces agglomerates susceptible to the loss of their advantages. Therefore, the proper functionalization of BNNTs is crucial to highlight their fundamental characteristics. Herein, a simplistic low-cost approach of BNNT surface modification through catechol-polyamine (CAPA) interfacial polymerization is postulated to improve its dispersibility on the polymeric matrix. The modified BNNT was assimilated as a filler additive with AlN/Al₂O₃ filling materials in a PDMS polymeric matrix to prepare a thermal interface material (TIM). The resulting composite exhibits a heightened isotropic thermal conductivity of 8.10 W/mK, which is a ~47.27% increase compared to pristine composite 5.50 W/mK, and this can be ascribed to the improved BNNT dispersion forming interconnected phonon pathways and the thermal interface resistance reduction due to its augmented compatibility with the polymeric matrix. Moreover, the fabricated composite manifests a fire resistance improvement of ~10% in LOI relative to the neat composite sample, which can be correlated to the thermal stability shift in the TGA and DTA data. An enhancement in thermal permanence is stipulated due to a melting point (Tm) shift of ∼38.5 °C upon the integration of BNNT-CAPA. This improvement can be associated with the good distribution and adhesion of BNNT-CAPA in the polymeric matrix, integrated with its inherent thermal stability, good charring capability, and free radical scavenging effect due to the presence of CAPA on its surface. This study offers new insights into BNNT utilization and its corresponding incorporation into the polymeric matrix, which provides a prospective direction in the preparation of multifunctional materials for electric devices.

In this study, a sustainable air plasma-based nitrogen fixation into reactive nitrogen species in water (e.g. nitrate and nitrite) is presented, which mimics the lightning-based nitrogen fixation that occurs in nature. We report a hybrid plasma system that combines a dielectric barrier discharge (DBD) reactor (as an efficient ozone source) and an arc plasma reactor (as an efficient NO _x source). This hybrid plasma system completely converts gaseous NO _x and O ₃ into NO x − in water with almost zero emissions (NO _x and O ₃ ). Gaseous outlets, in-liquid species, and electrical parameters were investigated. The energy cost for nitrate production via a single-pass reaction was extremely reduced to 8 MJ mol ⁻¹ , which enhanced the applicability of the direct one-step nitrogen fixation into NO x − in water for distributed fertilizer production to decrease the dependence on the Haber–Bosh process toward sustainable agricultural development.

The proliferation of natural gas production had led to increased utilization of methane as a raw material for chemicals. The most significant bottleneck in this process is the high activation energy of methane. This paper reports the direct conversion of methane to acetylene in a novel rotating arc driven by AC electrical power. By feeding a sufficiently high concentration of CH₄ (greater than 43%) diluted in H₂ (the discharge gas) through the arc column, a low specific energy requirement (SER) of 10.2 kW h kg⁻¹ C₂H₂ was achieved. The use of hydrogen as the discharge gas strongly suppressed soot formation during the methane conversion process under high methane concentration conditions, resulting in a carbon balance of greater than 95% and a C₂H₂ selectivity of greater than 90% while maintaining a methane conversion rate of greater than 70%, depending on the conditions. The novel rotating arc enabled the elongation of the arc column itself, which controlled heat loss and improved the energy use for reaction. The ability to control the arc length based on low-current type arc generation has additional benefits for reaction enhancement. These results demonstrate that arc control, optimization of the reaction conditions, and a full understanding of reaction pathway are viable means for the energy-efficient direct conversion of methane to acetylene.

Inspired by nature, tunable wettability has attracted a lot of attention in both academia and industry. Various methods of polymer surface tailoring have been studied to control the changes in wetting behavior. Polymers with a precisely controlled wetting behavior in a specific environment are blessed with a wealth of opportunities and potential applications exploitable in biomaterial engineering. Controlled wetting behavior can be obtained by combining surface chemistry and morphology. Plasma assisted polymer surface modification technique has played a significant part to control surface chemistry and morphology, thus improving the surface wetting properties of polymers in many applications. This review focuses on plasma polymerization and investigations regarding surface chemistry, surface wettability and coating kinetics, as well as coating stability. We begin with a brief overview of plasma polymerization; this includes growth mechanisms of plasma polymerization and influence of plasma parameters. Next, surface wettability and theoretical background structures and chemistry of superhydrophobic and superhydrophilic surfaces are discussed. In this review, a summary is made of recent work on tunable wettability by tailoring surface chemistry with physical appearance (i.e. substrate texture). The formation of smart polymer coatings, which adjust their surface wettability according to outside environment, including, pH, light, electric field and temperature, is also discussed. Finally, the applications of tunable wettability and pH responsiveness of polymer coatings in real life are addressed. This review should be of interest to plasma surface science communality particularly focused controlled wettability of smart polymer surfaces.

An energy efficient dry reforming process using a rotating arc plasma is introduced. By virtue of an elongated stable arc state in a rotating arc, a thermal energy efficiency of up to 76% and a reduction of the process costs to 9.4 and 5.52 kJ L⁻¹ for reactant conversion and syngas production, respectively, are realized. The effects of the CH₄/CO₂ molar ratio on the energy cost were also investigated. The lowest energy costs were obtained at molar ratios of 3/7 and 1 for the reactant conversion and syngas production, respectively. Moreover, we found that a specific energy input (SEI) of 11.2kJ L⁻¹ could maximize the conversion of both CO₂ and CH₄ to almost 100%. The results presented herein successfully demonstrate the commercial feasibility of using low‐temperature arcs for the dry reforming of methane.