Worawat Wattanathana

Novel Recovery of Nano-Structured Ceria (CeO2) from Ce(III)-Benzoxazine Dimer Complexes via Thermal Decomposition

N,N-bis(2-hydroxybenzyl)alkylamines, benzoxazine dimers, are the major product produced from benzoxazine monomers on mono-functional phenol by the one step ring opening reaction. Due to the metal responsive property of benzoxazine dimers, in this present work, N,N-bis(5-methyl-2-hydroxybenzyl)methylamine (MMD), N,N-bis (5-ethyl-2-hydroxybenzyl)methylamine (EMD), and N,N-bis(5-methoxy-2-hydroxybenzyl) methyl amine (MeMD), are considered as novel ligands for rare earth metal ion, such as cerium(III) ion. The complex formed when the clear and colorless solutions of cerium nitrate and benzoxazine dimers were mixed, results in a brown colored solution. The metal-ligand ratios determined by the molar ratio and the Job’s methods were found to be in a ratio of 1:6. To clarify the evidence of the complex formation mechanism, the interactions among protons in benzoxazine dimers both prior to and after the formation of complexes were determined by means of 1H-NMR, 2D-NMR and a computational simulation. The single phase ceria (CeO2) was successfully prepared by thermal decomposition of the Ce(III)-benzoxazine dimer complexes at 600 °C for 2 h, was then characterized using XRD. In addition, the ceria powder investigated by TEM is spherical with an average diameter of 20 nm.

The Effect of Alkali and Ce(III) Ions on the Response Properties of Benzoxazine Supramolecules Prepared via Molecular Assembly

A series of benzoxazine monomer supramolecules with different substituted groups on their benzene ring was prepared with a Mannich reaction and characterized by FTIR, 1H-NMR and MS. The obtained products were 3,4-dihydro-3-(2’-hydroxyethylene)-6-methyl-2H-benzoxazine (BM1), 3,4-dihydro-3-(2’-hydroxyethylene)-6-ethyl-2H-benz-oxazine (BM2), and 3,4-dihydro-3-(2’-hydroxyethylene)-6-methoxy-2H-benzoxazine (BM3). The efficiency of alkali metal ion extraction from the products was determined with Pedersen’s technique, while the complexation of the Ce(III) ion was confirmed by the Job’s and the mole ratio methods. The evidence of complex formation between benzoxazine monomers and Ce(III) ions was obtained with FTIR and a computational simulation. Single phase ceria (CeO2) as observed with XRD was successfully prepared by calcinating the Ce(III)-benzoxazine monomer complexes at 600 °C for 2 h. In addition, the geometry of the ceria nanoparticles confirmed by TEM is spherical, with an average diameter of 10‑20 nm.

Barium ferrite prepared by modified Pechini method: effects of chloride and nitrate counter ions on microstructures and magnetic properties

Barium hexaferrite powders were successfully prepared by the modified Pechini method using citrate and glycerol. The materials were prepared employing different Ba:Fe ratios, iron(III) precursors and calcination temperatures. The obtained powders were characterized by XRD, VSM, SEM, EDX and FT-IR. The Ba:Fe molar ratio of 1:11, for both chloride and nitrate series, is observed to be the optimal ratio to attain the phase-pure barium hexaferrite. Moreover, these barium hexaferrite powders synthesized with the Ba:Fe ratio of 1:11 showed the highest saturation magnetization among the samples in the same series. Interestingly, the powders formed from chloride precursors had significantly lower coercive fields than those from nitrate precursors, highlighting the role of counter ions. The reasons were likely to be the smaller particle sizes in materials obtained from the nitrate precursors and possibly the distortion of the barium hexaferrite structure due to the substitution of some oxide with the chloride species within the materials obtained in the chloride series.

Preparation of Palladium-Impregnated Ceria by Metal Complex Decomposition for Methane Steam Reforming Catalysis

Palladium-impregnated ceria materials were successfully prepared via an integrated procedure between a metal complex decomposition method and a microwave-assisted wetness impregnation. Firstly, ceria (CeO2) powders were synthesized by thermal decomposition of cerium(III) complexes prepared by using cerium(III) nitrate or cerium(III) chloride as a metal source to form a metal complex precursor with triethanolamine or benzoxazine dimer as an organic ligand. Palladium(II) nitrate was consequently introduced to the preformed ceria materials using wetness impregnation while applying microwave irradiation to assist dispersion of the dopant. The palladium-impregnated ceria materials were obtained by calcination under reduced atmosphere of 10% H2 in He stream at 700°C for 2 h. Characterization of the palladium-impregnated ceria materials reveals the influences of the metal complex precursors on the properties of the obtained materials. Interestingly, the palladium-impregnated ceria prepared from the cerium(III)-benzoxazine dimer complex revealed significantly higher BET specific surface area and higher content of the more active Pdδ

Dielectric and mechanical properties of poly(butylene succinate) thin film composites incorporated with barium strontium titanate powder

ABSTRACT High dielectric constant barium strontium titanate (Ba0.7Sr0.3TiO3 or BST) powder was prepared by sol-gel method for using as a filler in poly(butylene succinate) (PBS) composite with 0–3 connectivity system. Moreover, thermal and dielectric properties of poly(butylene succinate) integrated with BST powder were studied. The results showed the success of improving thermal stability and dielectric constant of poly(butylene-succinate) by increasing amount of BST powder. Therefore, the prepared PBS-BST composite thin films with good dielectric properties, flexibility, and processability could be applicable for the thin film capacitor for high-frequency electronic devices.

4,4'-Diethyl-2,2'-[(N-cyclo-hexyl-imino)-bis-(methyl-ene)]diphenol.

The title compound, C24H33NO2, exhibits an intramolecular hydrogen bond between a phenol –OH group and the N atom. In the crystal, molecules are connected by pairs of O—H⋯O hydrogen bonds.

2-{[(2-Hy­droxy-3,5-dimethyl­benz­yl)(meth­yl)amino]­meth­yl}-4,6-dimethyl­phenol

In the title compound, C19H25NO2, the dihedral angle between the benzene rings is 53.15 (8)°. One of the –OH groups forms an intramolecular O—H⋯N link, generating an S(6) ring. The other –OH group forms an intermolecular O—H⋯N hydrogen bond in the crystal, generating centrosymmetric R 2 2(20) loops.

Chapter 6 – 3,4-Dihydro-1,3-2H-Benzoxazines: Uses Other Than Making Polybenzoxazines

3,4-Dihydro-1,3-2H-benzoxazines, heterocyclic compounds consisting of benzene and oxazine rings, can be synthesized in a single step by Mannich reaction from primary amines, paraformaldehyde, and phenols. Consequently, various 3,4-dihydro-1,3-2H-benzoxazines have been synthesized by the combination of many amines and phenol derivatives. One of the 3,4-dihydro-1,3-2H-benzoxazines as bisphenol A-based benzoxazines has been used as monomers for preparation of novel phenol resins known as polybenzoxazines. However, the other practical applications of benzoxazines, apart from their use as monomers, are rarely reported. Therefore, due to the recent discovery of these other remarkable properties of benzoxazines, this chapter is, designed to demonstrate extra possibilities in the use of benzoxazines for such applications as luminescent materials, ligands for cations, and as reducing agents for precious metal ions.