Synthesis,Properties of Alkyl Azobenzene and their LB Films Properties

• Main Authors: Tung, Cheng-Chi, 董正琪
• Other Authors: Hong Chia-Hong
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/30193196119230368635

碩士 === 國立成功大學 === 化學工程學系 === 84 === In this study three types of aminoazobenzenes such as 4-Nitro-4'-N-(n-Octyl)azobenzene; 4-Nitro-4'-N-(n-Lauryl) azobenzene and 4-Nitro-4'-N,N-bis(n-Lauryl)azobenzene were prepared to study the monolayers properties on water surface. The monolayers of these aminoazobenzenes on water are found to be unstable.Therefore, stearic acid (SA) was added to improve their stability on water surface. It shows that the film stability and degree of molecular aggregation varies with the ratio of the aminoazobenzene and SA. <4-Nitro-4'-N-(n-Octyl) azo-benzen> shows the better stability and less aggregation monolayer with a ratiobetween 2:1 and 1:1. The phases and phase transitions of monolayer depends onthe length of substituted group, temperature and the kind as well as concentration of ions in the subphase. In this system, both reducing temperature andincreasing the length of substituted group could improve the stability of monolayer.The monolayer of mono- substituted aminoazobenzenes show expanded film ina wide range of surface pressure. However, that of di-substituted aminoazoben-ze ne shows expanded phase. The addition of Cd2+ ions into the subphase showsbetter stable monolayer comparing with Ca2+ ions reported elsewhere. The stability of monolayer increases with increasing ion concentration. Finally, thecrystal morphology of these aminoazobenzenes were also studied by using differential scanning calorimetry (DSC) and polarized optical microscope. 4-Nitro-4'-N,N-bis(n-Lauryl) azobenzene shows smectic liquid crystal phase. 4-Nitro-4'-N-(n- Octyl)azobenzene shows both smectic and nematicliquid crystal phases. However, 4-Nitro-4'-N-(n-Lauryl)azobenzene shows only two types of crystalline butno liquid crystal phase.