| A new series of azoic mesomorphic compounds HO-CnH2n-C6H4-N=N-C6H4-OC2H5 (abbr. as A)(n=2,4,6,8,10)containing hydroxyl groups have been synthesized through etherification, reduction and diazo reactions. Then by means of amination , hydrolysis and polyreaction , Ladderlike polysiloxane liquid crystals (abbr. as P) were synthesized. Which have the azo mesogen in the side chain. The structure of A compounds were characterized by the methods of 1H-NMR and IR. The influence of the number of carbon atoms in flexible spacer on their mesomorphic state, clear temperature, phase-transition temperature is studied by using of DSC. The result indicates that the compounds A can transform their mesomorphase from di-metamorphosis mesomorphase into mono-metamorphosis mesomorphase with increasing number of carbons(n=2,4,6,8,10) existing in the spacer. At the same time, compounds A's clear temperature decreases gradually except n=10. We explain the change tendency of clear temperature by W.H.Deieu theory and van der Waals forces theory.The liquid crystallinities of Ladderlike polysiloxane compounds were studied by the methods of DSC, X-ray, PLM and etc. They all display liquid crystallinities,and with increasing of the length of the flexible end-group,the clear temperature(Tcl),the temperature range (â–³T)and liquid crystal style are all regularly changed.
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