Liquid crystalline carbosilane dendrimers with terminal phenyl benzoate mesogenic groups: Influence of generation number on phase behaviour

The thermal behaviour of two series of liquid crystalline carbosilane dendr imers of generations 1 - 5 containing 8, 16, 32, 64 and 128 terminal phenyl benzoate mesogenic groups, respectively, was investigated by means of pola rising optical microscopy, DSC and X-ray methods. Mesogenic groups on the b ase of methoxybenzoic (anisic) acid (Anis) and methoxyphenol (MPhB) were li nked to the carbosilane dendritic matrices through -OOC-(CH2)(10)-Si(CH3)(2 )OSi(CH3)(2)- spacer. All LC dendrimers synthesised display smectic type me sophases and crystal phases over wide temperature region. LC dendrimers of fifth generation have more complex phase behaviour: heating the samples lea ds to transition from smectic to, most probably, columnar mesophases.