Carbosilane liquid crystalline dendrimers with terminal chiral mesogenic groups: structure and properties.

This paper presents a systematic study of two series of carbosilane liquid crystalline (LC) dendrimers from first to fifth generations bearing 8, 16, 32, 64 and 128 terminal chiral mesogenic groups, respectively. All the LC dendrimers synthesized are characterized by the same glass transition temperature around -5°C. It has been shown that the LC dendrimers of the lower generations (G-1-G-3) form a ferroelectric SmC* phase over a very broad temperature range up to about 180°C, while the LC dendrimers of the higher generations (G-4 and G-5) display a rectangular columnar mesophase (Col[sub r]). Schemes of packing in the SmC* and Col[sub r] mesophases formed by the LC dendrimers are suggested and discussed. Electrical measurements on the ferroelectric LC dendrimers have shown that an increase in generation number leads to a decrease in the value of the spontaneous polarization and an increase in switching time. [ABSTRACT FROM AUTHOR]