Hydroxyapatite (HA) is a material that has been widely applied to replace the damaged bone as a bone implant. Different types of HA have been successfully synthesized by a hydrothermal method based on calcium oxide (CaO) which was originated from chicken eggshells and diammonium hydrogen phosphate (DHP)/(NH₄)₂HPO₄ as their precursors. We present a novel approach to the hydrothermal synthesis of HA form eggshells as a new precursor via a one-step synthesis method. The influence of temperature was also observed to study the effect on the crystallinity, purity, and morphology of obtained HAs. The synthesis was carried out at two different temperatures, 200 °C (HA-200) and 230 °C (HA-230) for 48 h respectively. The structures, purities, and morphologies of hydroxyapatite were analyzed by X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR), and Scanning Electron Microscopy- Energy Dispersive Spectroscopy (SEM-EDS), and Transmission electron microscopy (TEM). The XRD patterns show the HA main phase indicated the purity of 96.5% for HA-200 and 99.5% for HA-230. The TEM micrograph suggested a hexagonal-like of HA with an average particle size of 92.61 nm. Hexagonal-like of HAs are suitable for bone implants and further application.

Polyaniline (PANI) has been widely used as an electroactive material in various applications including sensors, electrochromic devices, solar cells, electroluminescence, and electrochemical energy storage, owing to PANI’s unique redox properties. However, the chemical and electrochemical stability of PANI-based materials is not sufficiently high to maintain the performance of devices under many practical applications. Herein, we report a route to enhancing the chemical and electrochemical stability of PANI through layer-by-layer (LbL) assembly. PANI was assembled with different types of polyelectrolytes, and a comparative study between three different PANI-based layer-by-layer (LbL) films is presented here. Polyacids of different acidity and molecular structure, i.e., poly(acrylic acid) (PAA), polystyrene sulfonate (PSS), and tannic acid (TA), were used. The effect of polyacids’ acidity on film growth, conductivity, and chemical and electrochemical stability of PANI was investigated. The results showed that the film growth of the LbL system depended on the acidic strength of the polyacids. All LbL films exhibited improved chemical and electrochemical stability compared to PANI films. The doping level of PANI was strongly affected by the type of dopants, resulting in different chemical and electrochemical properties; the strongest polyacid (PSS) can provide the highest conductivity and chemical stability of conductive PANI. However, the electrochemical stability of PANI/PAA was found to be better than all the other films.

Improving the kinetics of electrochemical ion intercalation processes is of interest for realizing high-power electrochemical energy storage. This includes classical battery-like intercalation and pseudocapacitive intercalation processes with a capacitor-like electrochemical signature. Electrochemical methods are needed to probe the kinetics of such complex multistep processes in detail. Here, we present the use of the distribution of relaxation times (DRT) analysis of electrochemical impedance data to identify the kinetic limits of intercalation reactions. We study the lithium intercalation reaction in TiS₂ from organic and aqueous electrolytes as a model system. The material can exhibit both battery-like and pseudocapacitive intercalation regimes depending on the potential range, variable diffusion lengths by adjusting its particle size, and a tunable degree of solvent cointercalation by choosing the electrolyte solvent. Using DRT, we can distinguish between the kinetic limitations imposed by solid-state ion diffusion, interfacial ion adsorption and transport, and ion desolvation processes. Thus, DRT analysis can complement existing methods, such as voltammetry or 3D-Bode analysis, to better understand the kinetics of intercalation reactions.

High-density polyethylene (HDPE) is among the flexible polymers on account of its appropriate processability and adequate mechanical properties. Grafting reactive monomers such as glycidyl methacrylate (GMA) and maleic anhydride (MAH) onto polyethylene was one of the ultimate choices to improve the physicochemical properties of HDPE. MAH is an appropriate option for grafting onto HDPE owing to its low reactivity and it relatively undergoes a direct grafting onto the polymer. The grafting of MAH on HDPE copolymerization has been conducted using monomer microencapsulation method in this study. The monomer microencapsulation samples were extracted stratified using acetone and xylen. Samples were then analyzed using titration, melt flow rate, FTIR, DSC, TGA and C-NMR. The results showed the degree of paste monomer on HDPE with a microencapsulation method was greater when compared to the usual method. We were successfully improving the grafting degree of MAH onto HDPE by using a simple blending method. The pre-microencapsulated HDPE provided an increasing in grafting degree of 1.88% (HDPE-g-MAH) over the conventional one which shows the value of 1.39% (HDPE-g-MAH).

Fuel cell membrane of Nafion is commonly used as the electrolyte material of fuel cell which has good mechanical properties, but the hydrophobicity reduce its proton conductivity. Thus, the other polymer is used for the electrolyte membrane. A polymer modification of sulfonated poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) by attaching sulfonate group and oxide compounds such as sAl₂O₃ would enhance the proton conductivity. The research is aimed to modify PVDF-co-HFP via the addition of sAl₂O₃ or pristine Al₂O₃ and studying the effect of sulfonated Al₂O₃ on the conductivity. The research includes Al₂O₃ particles synthesis, the sulfonation of Al₂O₃, the membrane preparation, the sulfonation of membrane, and the characterisation of membrane using FTIR, SEM-EDX, and Four-point Probe Electrical Device Analysis. SEM-EDX analysis explained that the 6% addition of Al₂O₃ showed denser cross-sectioned membrane rather than the 9% addition of Al₂O₃. The highest conductivity achieved can be revealed at the 6% sAl₂O₃ addition on PVDF-co-HFP membrane as 2.27 × 10^-3 S cm^-1 which is higher than a previous study.