Papers by Author: Supagorn Rugmai

Abstract: The evaluation of PEG as a gelation solvent for an organogel based on β-cyclodextrin (β-CyD) was investigated using principal component analysis (PCA). The test tube tilting method was performed to examine the gel formation experimentally. The important descriptors used in the PCA included the Hansen partial solubility parameters. LogP may be able to be used as an additional descriptor for this system. According to PCA analysis, PEG was in a cluster of gelation solvents. Subsequently, various PEG liquid state grades were tested for their ability to gel the system and PEG400 was found to be able to produce a gel. This verifies that PCA can be successfully used to evaluate the role of PEG. Accordingly, this PCA method may be an effective tool to evaluate the role of any solvent for other low molecular weight gelators (LMWGs). Afterwards, the optimal components in the system were explored, and it was found to be 0.1M β-CyD, 0.5M K₂CO₃ in PEG400. Based on WAXS, the gel fiber of this organogel was demonstrated to be amorphous. This forming organogel will be further characterized in details and investigated for use in a drug delivery system.

Abstract: Magnetic fluid is a special class of materials which possesses the advantages of a liquid state of the carrier and a magnetic state of the particles. In addition to the conventional uses in mechanical engineering, magnetic fluids containing magnetite (Fe₃O₄) superparamagnetic nanoparticles are under research and development for drug delivery, hyperthermia and MRI contrast agents. On the other hand, iron-platinum (FePt) is investigated as materials for ultrahigh density recording. Before their assembly into patterned media, the as-synthesized FePt nanoparticles in superparamagnetic state are commonly stored in forms of magnetic fluids. In this work, iron-platinum (FePt) nanoparticles with their surface modified by oleic acid and oleyleamine were synthesized from the polyol process. The starting material was an environmental friendly iron(III) acetylacetonate and the products were dispersed in n-hexane. In small-angle X-ray scattering (SAXS) measurements at the Synchrotron Light Research Institute, Thailand, each magnetic fluid was injected into a sample cell with aluminum foil windows and the X-ray of wavelength 1.55 Å from BL2.2 was used. The measured SAXS intensity profiles as a function of the scattering vector from 0.27 to 2.30 nm^-1 were fitted and compared between two different reactions. Nanoparticles synthesized by using a higher amount of Fe(acac)₃ were matched with monodisperse spheres of radius 2.4±0.3 nm. The other reaction with a reducing agent gave rise to smaller nanoparticles of two size distributions. From this work, the potential of synchrotron radiation to complement conventional characterization techniques in the investigation of nanoparticles for high density recording and biomedical applications is underlined.

Abstract: The 0.98BaTiO₃-0.02Ba (Mg_1/3Nb_2/3) O₃ ceramics has been synthesized through a conventional mixed-oxide by using BT nanopowder and BMN micropowder. The phase purity of the powders and the ceramics was examined using X-ray diffraction (XRD). The 0.98BT-0.02BMN powders were sintered to 92% of the theoretical density at a temperature of 1300 °C for 2 h. The microstructure of the sintered surface was investigated using scanning electron microscopy (SEM). The dielectric constant (ε_r) and loss factor (tanδ) of the sintered pellets at Curie temperture were 3000 and 0.015, respectively.