Effect of the Spacer Length on the Solid Phase Transitions of Asymmetric Gemini Surfactants (CROSBI ID 483929)
Prilog sa skupa u zborniku | sažetak izlaganja sa skupa | domaća recenzija
Podaci o odgovornosti
Sikirić, Maja ; Šmit, Ivan ; Tušek-Božić, Ljerka ; Primožič, Ines ; Filipović-Vinceković, Nada
engleski
Effect of the Spacer Length on the Solid Phase Transitions of Asymmetric Gemini Surfactants
Three quaternary, asymmetric, dimeric surfactants with two hydrocarbon chains differing in length (tetradecyl and dodecyl) and with different polymethylene spacers N, N, N¢ , N¢ -tetramethylethane (12-2-14), N, N, N¢ , N¢ -tetramethylehexane (12-6-14) and N, N, N¢ , N¢ - tetramethyldecane (12-10-14) were prepared. Their solid phase and thermal behavior were examined by X-ray diffraction, spectral, thermal and optical microscopic studies. Structure of 12-2-14 contains interdigitated alkyl chain layers, 12-6-14 monolayers of molecules with tilted alkyl chains, while 12-10-14 exhibits liquid crystalline structure even at room temperature. Molecules with a shorter spacer are all in cis-configuration, while those with longer ones are all in trans-configuration. On heating all compounds exhibited the conformational disordering of the alkyl chain during phase transitions in the solid state at lower temperatures and the bidimensional disordering of the ionic layers during the solid crystalline to liquid crystalline transitions. Phase transitions in the solid state include structural varieties, polymorphs and smectic liquid crystals. Crystal structure, number of phase transitions and thermodynamic parameters strongly depend on the spacer length ; i.e., on the global configuration of molecules. Temperatures of the first solid state, solid crystal – liquid crystal and liquid crystal – isotropic melt transitions exhibit maximum for s = 6. Polarizing microscopy revealed characteristic textures of the smectic phases in the case of 12-2-14 and 12-10-14.
gemini surfactants ; thermal properties ; polymorphism ; thremotropic liquid crystals
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Podaci o prilogu
29-29.
2003.
objavljeno
Podaci o matičnoj publikaciji
XVIII. Hrvatski skup kemičara i kemijskih inženjera : sažeci
Zrnčić, Hrvoje
Zagreb: Hrvatsko društvo kemijskih inženjera i tehnologa (HDKI) ; Hrvatsko kemijsko drustvo
953-65894-08-4
Podaci o skupu
XVIII.Hrvatski skup kemičara i kemijskih inženjera,
poster
16.02.2003-19.02.2003
Zagreb, Hrvatska