Comparison of pristine and polyaniline-grafted MWCNTs as conductive sensor elements for phase change materials: Thermal conductivity trend analysis

Development of an Efficient Voltammetric Sensor for the Monitoring of 4-Aminophenol Based on Flexible Laser Induced Graphene Electrodes Modified with MWCNT-PANI

Sensitive electrodes are of a great importance for the realization of highly performant electrochemical sensors for field application. In the present work, a laser-induced carbon (LIC) electrode is proposed for 4-Aminophenol (4-AP) electrochemical sensors. The electrode is patterned on a commercial low-cost polyimide (Kapton) sheet and functionalized with a multi-walled carbon nanotubes polyaniline (MWCNT-PANI) composite, realized by an in-situ-polymerization in an acidic medium. The LIC electrode modified with MWCNT-PAPNI nanocomposite was investigated by SEM, AFM, and electrochemically in the presence of ferri-ferrocyanide [Fe(CN)6]3-/4- by cyclic voltammetry and impedance spectroscopy. The results show a significant improvement of the electron transfer rate after the electrode functionalization in the presence of the redox mediators [Fe(CN)6]3-/4-, related directly to the active surface, which itself increased by about 18.13% compared with the bare LIG. The novel electrode shows a good reproducibility and a stability for 20 cycles and more. It has a significantly enhanced electro-catalytic activity towards electrooxidation reaction of 4-AP inferring positive synergistic effects between carbon nanotubes and polyaniline PANI. The presented electrode combination LIC/MWCNT-PANI exhibits a detection limit of 0.006 μM for the determination of 4-AP at concentrations ranging from 0.1 μM to 55 μM and was successfully applied for the monitoring in real samples with good recoveries.

Theory for designing mechanically stable single- and double-walled SiGe nanopeapods

Herein, we utilized molecular dynamic (MD) simulations using LAMMPS software and selecting Tersoff and Lennard-Jones potentials to design and investigate mechanical properties of (8,8), (9,9), (10,10), and (11,11) single-walled and (8,8)@(11,11) double-walled silicon-germanium (SiGe) armchair nanopeapods. The number of encapsulated fullerenes and the working temperature were changed as variables to evaluate the mechanical properties. The larger nanopeapods had lower Young's modulus and failure strain, but, surprisingly enough, no significant variation was found in failure strain values by increasing the number of Si₃₀Ge₃₀ cages and the temperature (300-900 K). Overall, higher mechanical properties were the case for double-walled SiGe nanopeapods and that the more the number of encapsulated cages, the lower the mechanical properties whatever the nanopeapod. Amazingly, fullerenes remained undamaged even after the SiGe nanopeapods ruptured. Thus, thermally/mechanically stable nanopeapods developed theoretically herein can be considered potential super-carriers for drug and gene encapsulation.

Thermal energy storage and thermal conductivity properties of Octadecanol-MWCNT composite PCMs as promising organic heat storage materials

Fatty alcohols have been identified as promising organic phase change materials (PCMs) for thermal energy storage, because of their suitable temperature range, nontoxicity and can be obtained from both natural and synthetic sources. Like all other organic PCMs, octadecanol (OD) as PCM suffers from low thermal conductivity (TC). In this work, to enhance its TC, it was grafted on the functionalized MWCNT and were used as a conductive filler to enhance overall thermal properties of OD in a composite PCM (CPCMs) structure. The OD/OD-g-MWCNT sample showed better dispersion within the composites and the presence of additional OD boosted the overall heat storage enthalpy compared to that of plane composite sample with OD/MWCNT. In a non-quantitative approach, it was observed that, any increase in grafting ratio of OD increases the heat storage enthalpy of the composites. The heat storage enthalpy of (267.7 J/g) OD/OD-g-MWCNT(4:1)-5wt% composite PCM had reached very close to the heat storage enthalpy value of pure OD (269.3 J/g), and much higher than that of OD/MWCNT-5wt% (234.5 J/g). Champion sample i.e. OD/OD-g-MWCNT (4:1)-5wt%, showed good heat storage enthalpy, cycling performance, thermal stability and TC enhancement by 262.5%.