| 초록 |
Liquid crystalline urethane-urea molecule (LCUU) was prepared via stepwise synthetic method from mono-methoxy poly(ethylene) glycol(M.W.=2000gmol-1) (mPEG), 4,4'-methylenedi-p-phenyl diisocyanate (MDI), and 4,4'-azodianilline (ADA). In the 1st step, ADA and MDI were reacted to form NCO-terminated mesogenic molecular unit. In the 2nd step, the mesogenic unit was reacted with the excess amount of mPEG to form LCUU having urethane-urea linkage. Thermal analysis(DSC) and optical images (POM) revealed the liquid-crystal properties of the LCUU. The LCUU showed surface activity in water solution and CAC (critical aggregate concentration) of the LCUU in the presence of LiCF3SO3 was obtained by surface tension analysis. Near the CMC, the LCUU aggregates in the water-ethanol solution were observed by TEM and AFM analyses. The effect of reversible photo (UV) and thermal isomerization of ADA in the mesogenic unit on liquid crystal behavior of the LCUU will be discussed. |
