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Natechanok Chansorn,Sujitra Amnuaypanich,Siriwat Soontaranon,Supagorn Rugmai,Sittipong Amnuaypanich 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.112 No.-
Solketal, a fuel additive, was synthesized from the solvent-free ketalization reaction of glycerol and acetoneusing phosphotungstic acid (PTA) catalysts. Due to strong acidity, PTA is expected to serve as an efficientacid catalyst, however low specific surface area of bulk PTA and the deactivation, by water,denounces its acid activity leading to low solketal production. The present study demonstrates a successin increasing the solketal yield in the ketalization catalyzed by PTA immobilized in the layer of poly(Nmethyl-4-vinylpyridinium) grafted on silica nanoparticles (SNSs-g-PMVP/PTA). PTA with the size of 1–2 nm were dispersed in the grafted-layer of PMVP under strong binding to positively charged pyridiniumwhile the grafted-PMVP provided the hydrophobic environment improving the water-tolerance of PTA. Inaddition, acid-base interactions between PTA and the pyridine group in the grafted-PMVP transformedPTA hexahydrate to PTA trihydrate. Using SNSs-g-PMVP/PTA catalyst resulted in increasing of the solketalyield above 90% within an hour of the glycerol ketalization compared with 17% yield of solketal in theketalization catalyzed by unsupported PTA.
Phinjaroenphan, Rarm,Kim, Young Yong,Ree, Brian J.,Isono, Takuya,Lee, Jinseok,Rugmai, Supagorn,Kim, Heesoo,Maensiri, Santi,Kakuchi, Toyoji,Satoh, Toshifumi,Ree, Moonhor American Chemical Society 2015 Macromolecules Vol.48 No.16
<P>Two series of crystalline-crystalline miktoarm star polymers were prepared and their thin film morphologies were investigated in detail by synchrotron grazing incidence X-ray scattering (GIXS): poly(n-hexyl isocyanate)(5000) poly(epsilon-caprolactone) (1-3)(17000) (PHIC(5k)-PCL1-3(17k)) and poly(n-hexyl isocyanate) (10000) poly(epsilon-caprolactone)(1-3)(10000) (PHIC(10k)-PCL1-3(10k)). In addition, their thermal properties were examined. All miktoarm star polymers revealed a two-step thermal degradation behavior where the PHIC arm was degraded first, followed by the PCL arm underwent degradation. Interestingly, all miktoarms were found to show a highly enhanced thermal stability, regardless of their molecular weight over 3k to 17k, which might be attributed to their one-end group capped with the counterpart arm(s) via arm-joint formation. Surprisingly, all miktoarm star polymers always developed only lamellar structure in toluene- and chloroform-annealed films via phase-separation, regardless of the length of PHIC arm as well as the length and number of PCL arm. Despite having highly imbalanced volume fractions, lamellar structure was constructed in the films of miktoarm star polymers through the override of volume fraction rule based on the rigid chain properties, self-assembling characteristics, conformational asymmetry, and compressibilities of PHIC and PCL arms. Furthermore, the orientation of such lamellar structures was controlled by the selection of either toluene or chloroform in the solvent-annealing process. The PHIC arm phases in the lamellar structures favorably formed a mixture of edge-on and face-on structures with fully extended backbone and bristle conformations even under the confined lamellar geometry and arm-joint. The PCL arm phases still crystallized, forming fringed-micelle like structures in which orthorhombic crystals were laterally grown along the in-plane direction of lamellae although their crystallization was somewhat suppressed by the confined lamellar geometry and arm-joint. Overall, crystalline-crystalline PHIC-PCL1-3 miktoarm polymers demonstrated very interesting but unusual, very complex hierarchical structures in the solvent-annealed thin films.</P>
Small-Angle X-Ray Scattering Study on PVA/Fe3O4 Magnetic Hydrogels
Sunaryono,Ahmad Taufiq,Edy Giri Rahman Putra,Atsushi Okazawa,Isao Watanabe,Norimichi Kojima,Supagorn Rugmai,Siriwat Soontaranon,Mohammad Zainuri,Triwikantoro,Suminar Pratapa,Darminto 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.3
A synchrotron small-angle X-ray scattering (SAXS) study on PVA/Fe3O4 magnetic hydrogels has been performed to investigate the effect of clustering on their magnetic properties. The hydrogels were prepared through freezing–thawing (F–T) processes. The structure, morphology and magnetic properties of magnetite (Fe3O4) nanoparticles (NPs) were investigated using X-ray diffractometry (XRD), transmission electron microscopy (TEM) and a superconducting quantum interference device (SQUID) magnetometer, respectively. In this study, SAXS data were used to reveal the structural dimensions of the magnetite and its distribution in the polymer-rich PVA and magnetic hydrogels. As calculated using the Beaucage and Teubner–Strey models, the average of the structural dimensions of the PVA hydrogels was 3.9 nm (crystallites), while the average distance between crystallites was approximately 18 nm. Further analysis by applying a two-lognormal distribution showed that the magnetite NPs comprised secondary particles with a diameter of 9.6 nm that were structured by primary particles (~3.2 nm). A two-lognormal distribution function has also been used in describing the size distributions of magnetite NPs in magnetic hydrogels. The clusters of magnetite NPs in the magnetic hydrogels are significantly reduced from 30.4 nm to 12.8 nm with decreasing concentration of the NPs magnetite from 15 wt.% to 1 wt.%. The saturation magnetization values of the magnetite NPs, the 15% and 1% magnetic hydrogels were 34.67 emu/g, 6.52 emu/g and 0.37 emu/g, respectively.