Two liquid crystal monomers,cholesteryl 10\|undecylenate (M1), and cholesteryl 4\|(10\|undecylenoyloxy)\|benzoate(M2),and their respective side\|chain liquid crystal homopolymers (P1,P2) were synthesized.Their liquid crystal properties were characterized by POM and DSC method.M1 could form sematic liquid crystal and cholesteric liquid crystal,while M2\|only cholesteric liquid crystal.The Polymers,P1 and P2,exhibited sematic liquid crystal behavior.The results also indicated that,because of the structure of 1,4\|COO\|Ar\|COO\|in M2 and P2,the isotropization tempretures of the liquid crystalline M2 and P2 were higher than those of M1 and P1,respectively,and the temprature range of LC phases of M2 was also wider than that of M1.Homopolymer P1,was applied in the capillary column gas chromatography as a novel stationary phase and showed ideal separating selectivity.A mixture of anthracene,phenanthrene and acenaphene and a mixture of dichlorobenzene isomers were well separated.
A series of novel pentaerythritol-based carbosilane dendrimers have been synthesized. Using pentaerythritol-based tetraallyl ether as core molecule, the dendrimers have been prepared up to the third generation with 108 allyl groups on the periphery by alternate allylation-hydro- silylation approach.
The photochromism of a 36-armed liquid crystalline dendrimer D6 was briefly described in this paper. The molar absorption coefficient, photoisomerization and photo back-isomerization of D6 in solution were investigated by UV/Vis absorption spectra. The results indicate that the photochromism and photo back-isomerization of D6 in chloroform (CHCl3) and tetrahydrofuran (THF) solutions are in accordance with the first order kinetics. The photochromism rate constants of D6 are 10-1 s-1, it is 107 times larger than that of side-chain liquid crystalline polymers containing the same azobenzene moieties.
