Abstract

Two classes of liquid crystalline hyperbranched copolyesters were prepared by the copolycondensation of silylated 3,5-bis(acetoxy)benzoic acid with mixtures of mesogenic difunctional monomers. The first class of LC-copolyesters was obtained from 1 : 1 mixtures (molar ratio) of silylated β-(4-acetoxyphenyl)propionic acid and silylated 4-acetoxybenzoic acid (poly(HPPA/HBA)). The second class of LC-copolyesters was obtained by additional copolycondensation of silylated 6-acetoxy-2-naphthoic acid. The hyperbranched copolyesters of this ternary system poly(HPPA/HBA/HNA) proved to be less crystalline in contrast to the binary system. In both classes of LC-copolyesters the degree of branching was varied via the feed ratio of 3,5-dihydroxybenzoic acid. A minimum segment length of 6 difunctional monomer units between the branching points is required to establish a nematic phase. However, a greater segment length is needed to obtain a homogeneous LC-phase. The poly(HPPA/HBA) copolyesters were also characterized by melt rheology. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1397–1405, 1998

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