Dilatometric study on phase transitions of benzylidene-p-n-hexadecyl/ Hexadecyloxy anilines (5.O16, 5O.O16 and 5.16)

摘要

Synthesis, characterization and phase transition studies (Dilatometry) have been carried out on three mesomorphic Schiff base compounds viz., N-(p-n-pentyl benzylidene)-p-n-hexadecyloxy aniline, 5.O16, N-(p-n-pentyloxy benzylidene)-p-n-hexadecyloxy aniline 5O.O16 and N-(p-n-pentyl benzylidene)-p-n-hexadecyl aniline, 5.16. The liquid crystalline phase identification and the phase transition temperatures have been carried out using SDTECHS polarising microscope attached with temperature controller with accuracy of ± 0.1 °C and for the conformation of the phase identification and the textures observed are compared with the standard textures. Further, the phase transition temperatures and the corresponding heats of transition across the phase transitions are recorded using DSC (Perkin Elmer). The characterization studies reveal that these compounds exhibit NG, N and A phase variants respectively. The nature of the phase transitions are studied through density results using dilatometric technique. The phase transitions exhibit first order nature in all the cases as expected. The results are discussed in the light of the body of the data available on other Schiff base compounds and on 5O.16.