Synthesis and mesomorphic properties of side-chain liquid crystalline ionomers containing sulfonic acid groups

Side-chain liquid crystalline ionomers containing M-2 (4-allyoxybenzoyloxy-4'-amylbenzoyloxy biphenyl) as mesogenic units and M-2 (4-undecylenicoxy-4'-phenylazobenzene sulfonic acid) as ionic units were synthesized by graft copolymerization. Their liquid crystalline properties were characterized by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction measurements. The results showed that introduction of nonmesogenic ionic units into polymeric structure could cause additional reduction of the clearing point of the ionomers, compared with the corresponding nonion polymers. When the content of ionic units increased to 8.5%, the ionic clusters and mesogens in the ionomers may be dispersed each other to form multiple blocks, but the introduction of ionic groups in LCIs did not change their mesogenic type. (c) 2007 Wiley Periodicals, Inc.