Structure-property relationships of smectic liquid crystalline polyacrylates as revealed by SAXS

Abstract

A influência da estrutura química dos grupos mesogênicos e do tamanho dos grupos espaçadores, no comportamento de fase de uma série de cristais líquidos poliméricos de cadeia lateral (SCLCP), foram estudados utilizando-se espalhamento de raios-X a Baixo Ângulo (SAXS) e Microscopia Ótica de Luz Polarizada (POM). Análises do arranjo das mesofases em amostras não orientadas e orientadas por ação do campo magnético são descritas. O papel do tamanho do espaçador lateral no empacotamento local e na largura da camada esmética determinados nas mesofases SmA e SmC é elucidado. Os ângulos θ formados entre os grupos mesogênicos e a normal às camadas nas mesofases SmC foram determinados. Um estudo a respeito do grau de ordem em função da temperatura, para os polímeros esméticos foi possível através de medidas de SAXS. Uma ordenação particular em um dos SCLCPs estudados é relacionada com a coexistência de duas fases distintas.The influence of the chemical structure of the mesogenic groups and the length of the spacer groups on the phase behavior in a series of side-chain liquid crystalline polyacrylates (SCLCP) have been studied using Small Angle X-ray Scattering (SAXS) and Polarized Optical Microscopy (POM). Analyses of the mesophase arrangement in unaligned and aligned samples by magnetic field are reported. The role of the spacer length on the local packing and on the thickness of the layers encountered in the SmA and SmC mesophases is elucidated. The tilt angles θ of the mesogenic cores related to the normal of the layers in the SmC mesophases are measured. A study about the degree of order as a function of temperature for the smectic polymers was possible using SAXS measurements. A particular arrangement in one of the studied SCLCPs is related to the coexistence of two different phases.

Influence of Alkyl Chain Spacer Length on the Charge Carrier Mobility of Isotactic Poly(N-carbazolylalkyl acrylates)

“…36 Later work has shown that μ h was increased with tacticity for PVK. 37 However, there are several structural variables that can potentially influence μ h , including the main chain, pendant group, spacer, and stereoregularity, 38,39 and understanding the structure−function relationships is essential for designing higher performing polymers. In our previous report on PCzEA, the alkyl spacer was kept constant at two carbons, and only the effect of stereoregularity on μ h was studied.…”

Insight into Out‐of‐Layer Fluctuations in the Smectic A Stability of 3,5‐Diarylisoxazole Liquid Crystals

“…On the other hand, hydroxyl groups stabilize more the smectic mesophase as evidenced by values of Σ, being a consequence of intermolecular association between the terminal hydroxyl groups by hydrogen bonds . As well exemplified by Laschat and others, the expansion of the layers upon heating and cooling cycles can be discussed in terms of the rod‐like molecules motion, by moving up and down as the temperature decreases, thus increasing the thickness of the layers.…”

Thermotropic liquid crystalline polyesters derived from 2-chloro hydroquinone

“…Polyester PE-7, wherein 10 methyelene Figure 2. 20 This is because when the number of methylene units is more than 8 side chain crystallization occurs and thus, nematic liquid crystal phase turns to more ordered smectic phase.…”