Naslov
Phase Transitions in Asymmetric Catanionic Surfactant

Autori
Tomašić, Vlasta ; Popović, Stanko ; Filipović-Vinceković, Nada

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Seventh Slovenian-Croatian Crystallographic Meeting, Book of Abstracts / Leban, Ivan - Ljubljana : Fakulteta za kemijo in kemijsko tehnologijo Univerze v Ljubljani, 1998, 33-33

Skup
7th Slovenian-Croatian Crystallographic Meeting

Mjesto i datum
Radenci, Slovenija, 18.06.1998. - 20.06.1998

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
catanionic surfactants; phase transition; polymorphism

Sažetak
Three novel catanionic surfactant were prepared from an equimolar mixture of catanionic (hexadecyltrimethylammonium bromide) and anionic (sodium alkyl sulfate, having the chain length C10, C12 and C14) surfactants. The physical and chemical properties of the prepared hexadecyltrimethylammonium alkyl sulfates were studied by different analytical methods: IR, 1H NMR, DSC, XRD, microscopy. According to DSC and XRD these compounds exhibited several phase transitions: solid crystalline-solid crystalline, solid crystalline-liquid crystalline, liquid crystalline-isotropic liquid phase. On heating, solid crystalline-solid crystalline phase transition manifested in a discontinuous increase of the long spacing. For instance, for the compound "C16-C14" this transition took place at 359 K, and the long spacing amounted 40.3(3) A at 358 K and 42.2(3) A at 360 K, this being a relative change of 4.7 %. Other phase transitions related to rearrangements in the crystal lattice in directions different from that of the long spacing, changes in conformation and finally the transition to a phase amorphous for XRD. On cooling, the compounds underwent reversible changes, exhibiting a temperature hysteresis. However, diffraction lines were much sharper and more intense than those observed on heating, this indicating an advanced ordering in the crystal lattice. Changes in relative intensities of diffraction lines took place due to a different orientation of crystal grains after crystallization. More details on the structure, properties and thermal behaviour are given elsewhere (Ber. Busenges. Phys. Chem. 101 (1997) 1942-1948).

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA