Synthesis of novel liquid crystalline poly(meth)acrylates containing siloxane spacer and terphenylene mesogenic unit

Novel side-chain liquid-crystalline poly(meth)acrylates were synthesized us ing 1-(3-hydroxyl-propyl)-3-[(4 "-cyano-p-terphenyloxycarbonyl)alkyl]-1,1,3 ,3-tetramethyldisiloxane as the key intermediate. The polymers used a disil oxane moiety as decoupling spacer with cyano-p-terphenyl as mesogenic unit. The products were characterized by NMR, GPC, DSC and polarizing optical mi croscopy. All the polymers with cyano-p-terphenyl mesogens formed a stable mesophase. However, if the mesogenic unit is replaced by cyano-p-biphenyl, the liquid crystalline character will be lost. The results also showed that the decoupling is incomplete even if a complex and very flexible decouplin g spacer is deliberately incorporated to obtain the highest possible decoup ling effect.