An X‐ray investigation of terminally carboxyl oligo (ethylene oxide) monomethyl ethers‐substituted side‐chain liquid crystalline polysiloxanes

Abstract

SYNOPSIS4'-[ Oligo (ethylene oxide) monomethyl ether carbonyl] biphenyl-4-yl4-(alkenyloxy ) benzoate side-chain liquid crystalline (LC) polysiloxane polymers with various lengths of a terminal group and spacer were prepared. The mesophase structure and transition temperature of those polymers were investigated using methods of X-ray diffraction, polarized optical microscopy, and differential scanning calorimetry, respectively. The mesophases of the polymers were smectic ones. The layer spacing d l s and the side-chain distance of d2s obtained were around 29-34 8 and 4.4-4.6 8, respectively. d 1s were much shorter than twice the lengths of the side chains presumed in the fully extended conformation. Hence, the two-layer end-on packings or the packing with overlapping of tails model seemed not able to interpret the mesophase structure of those polymers studied. The effects of temperature on the mesophase microstructure of 4'-[ethylene oxide monomethyl ether carbonyl] biphenyl-4-yl 4-(pentenyloxy ) benzoate side-chain LC polysiloxane polymer were also studied using the X-ray diffraction method. It was found that both d 1 and d 2 of the polymer in the mesophase temperature range became shorter with decreasing temperature and the long-and sbort-range order could remain, to some extent, at temperatures above the isotropic transition temperature and temperatures below the melting temperature. 0 1993

Probing the Texture of the Calamitic Liquid Crystalline Dimer of 4-(4-Pentenyloxy)benzoic Acid

“…Calamitic (rod-like) liquid crystals based on p -alkoxybenzoic acid were investigated earlier for their liquid crystalline properties [ 3 , 4 ]; and have recently gained increased interest for the design of a variety of liquid crystalline compounds [ 5 , 6 , 7 , 8 , 9 ]. Alkenyloxybenzoate monomers are a functionalized version of alkoxybenzoates, and, due to the alkene functionality at the molecule’s terminus, has also gained special attention in designing functionalized liquid crystalline materials; such as, liquid crystalline elastomers [ 5 , 6 , 7 , 8 , 9 ].…”

“…Calamitic (rod-like) liquid crystals based on p -alkoxybenzoic acid were investigated earlier for their liquid crystalline properties [ 3 , 4 ]; and have recently gained increased interest for the design of a variety of liquid crystalline compounds [ 5 , 6 , 7 , 8 , 9 ]. Alkenyloxybenzoate monomers are a functionalized version of alkoxybenzoates, and, due to the alkene functionality at the molecule’s terminus, has also gained special attention in designing functionalized liquid crystalline materials; such as, liquid crystalline elastomers [ 5 , 6 , 7 , 8 , 9 ]. Many physical properties of alkoxy and alkenoxy benzoic acid structures have been investigated, including their properties in binary systems [ 10 ], intermolecular hydrogen bonding formation [ 11 , 12 , 13 ], IR, Raman and thermodynamic investigations [ 14 ], the temperature dependence of their Raman spectra [ 15 ], the degree of order determination using IR dichroism [ 16 ], dielectric anisotropy [ 17 ] and their self assembly [ 18 ].…”

Synthesis, Characterization and Texture Observations of Calamitic Liquid Crystalline Compounds

“…However, the terminal end of the compounds were unfunctionalized linear aliphatic chains. On the other hand, alkenyloxy benzoate monomers are a functionalized version of alkoxy benzoate, a construct that also gained special attention in the design of functionalized liquid crystalline materials [ 11 – 15 ].…”