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Simultaneous synchrotron radiation X‐ray diffraction‐DSC analysis of melting and crystallization behavior of trilauroylglycerol in nanoparticles of oil‐in‐water emulsion
Author(s) -
Higami M.,
Ueno S.,
Segawa T.,
Iwanami K.,
Sato K.
Publication year - 2003
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-003-0765-2
Subject(s) - small angle x ray scattering , materials science , crystallization , nanoparticle , differential scanning calorimetry , emulsion , synchrotron radiation , chemical engineering , melting point , analytical chemistry (journal) , crystallography , scattering , composite material , chemistry , chromatography , thermodynamics , nanotechnology , optics , physics , engineering
Crystallization, polymorphic transformation, and melting behavior of nanoparticles of trilauroylglycerol (LLL) in oil‐in‐water (O/W) emulsion were examined initially by DSC, and then by simultaneous synchrotron radiation small‐angle (SAXS) and wide‐angle (WAXS) X‐ray diffraction and DSC (SR‐SAXS /WAXS/DSC). The O/W nanoparticles emulsions having average diameters of 42 to 120 nm were prepared by application of mechanical shear using a high‐pressure homogenizer. The following results were obtained: (i) The DSC study showed that the melting temperature of the stable β form of LLL was reduced from 46.7 (bulk) to 26.5–44.0°C (nanoparticles); this variation as assumed to be due to the size distribution of the nanoparticles. Crystallization temperature was also reduced from 18.9 (bulk) to −9.5±0.5°C (nanoparticles). These results were consistent with those of previous studies of nanoparticles of fats obtained in the O/W emulsion. (ii) The results obtained by the SR‐SAXS/WAXS/DSC technique during the cooling process to −20°C showed that the first‐occurring polymorph of LLL in the bulk liquid was β′, whereas α was first nucleated and transformed to β′ around −10°C during cooling in the nanoparticles. (iii) The SR‐SAXS/WAXS/DSC data taken during the heating process from −20°C after the crystallization showed that β′ transformed to β around 0°C and that the melting of β started at 30°C and ended at 44°C. The present study showed that forming nanoparticles of LLL in the O/W emulsion having the diameters of 42 to 120 nm reduced the melting and crystallization temperatures and increased the transformation rate of α→β′→β in comparison to the LLL crystals formed in the bulk phase.