Series Of Liquid Crystal Polymers Research Articles

Cholesteric liquid crystalline polysiloxanes containing furan ring with selective reflection – synthesis and properties

ABSTRACT In this paper, first series of liquid crystal polymers (PF) synthesised by hydrosilylation of monomer containing furan group (MA), monomer containing cholesterol group (MB), monomer containing D (+)-camphoric acid group (MC) and monomer containing cyano-group (MD), catalysed by platinum catalyst. Another series of liquid crystal polymers (EF) is synthesised by the Dies-Alder reaction of the former series and cross-linker containing bismaleimide group. The results of Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance(1H NMR) showed the successful preparation of various monomers as well as polymers. The thermal properties of two series were characterised by differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). We observed dramatic colour changes and Grand-jean textures of polymers using polarised optical macroscope (POM). The results of POM and selective reflection showed that both series of polymers are cholesteric liquid crystals. In the latter series, crosslinking by Diels-Alder reaction can make the liquid crystal better oriented, which can maintain their wonderful liquid crystal (LC) texture and selective reflection, and at the same time, it has a certain regulation effect on the appearance of cholesteric Grand-jean blue texture. The results of X-ray diffraction (XRD) further proved the two series of polymers are cholesteric liquid crystals.

Synthesis and characterisation of novel aromatic ester swallow-tailed cholesteric liquid crystal polymers

ABSTRACT In this paper, two novel aromatic ester swallow-tailed liquid crystal monomers M1 and M2 and a straight chain cholesteric liquid crystal monomer M3 were designed and synthesised. Two series of liquid crystal polymers, P1 series and P2 series, were graft-copolymerised with M and polymethylhydrosiloxane (PHMS). All the synthesised liquid crystal monomers and polymers were characterised by IR and 1H NMR and confirmed to the predicted molecular structure. The liquid crystal and thermal properties of the synthesised compounds were tested by DSC, POM, TGA and optical rotation. The results show that the monomer M1 is a monotropic nematic liquid crystal, and the Schlieren texture appears during the cooling process. M2 is an enantiotropic nematic liquid crystal with filamentous and schlieren texture. M3 is a thermotropic enantiotropic cholesteric phase with oily streak and focal cone texture. Both polymers P1 and P2 show typical Grand-Jean texture, and with the increase of monomer M3 content, the polymer clearing point temperature Ti increases continuously, the liquid crystal mesophase range widens, and the specific rotation value increases.

Polarized Emission Behavior of Pt Complex-Doped Polymer Films

Organic light-emitting diodes (OLEDs) based on conjugated polymers exhibiting polarized emission have attracted much attention because of their potential as backlights for conventional liquid crystal (LC) displays and 3-D displays. We have reported a new series of LC polymers based on donor-acceptor architecture containing an oxadiazole (OXD) and several amine moieties in the same side chain, which exhibit bipolar character with a wide energy band gap. In this study, to develop phosphorescent OLEDs with polarized emission, we synthesized a platinum complex, Pt(4-decyloxy)salen, with emitting property, and fabricated the device consisting of Pt complex as a guest and LC polymers as a host material. The Pt complex exhibited high thermal stability, good solubility and an emission peak at 530 nm in dichloromethane. To obtain electroluminescense from the Pt complex, we fabricated ITO/rubbed PEDOT:PSS/Pt(4-decyloxy)salen:host polymer/MgAg devices. The devices emitted a yellowish green light, which was dominated by the triplet emission of the platinum complex. In addition, polarized electroluminescence was observed in an aligned LC polymer film.

Palladium complexes of side‐chain liquid crystal polymers with T‐shaped two‐dimensional mesogenic units

AbstractA series of liquid crystal polymers (LCPs) with T‐shaped two‐dimensional mesogenic units were synthesized via solution polycondensation. The LCPs were used as ligand polymers to coordinate with palladium dichloride, by which a series of polymeric palladium complexes were prepared. The liquid crystalline behaviors of the compounds were characterized using differential scanning calorimetry, polarized microscopy and X‐ray diffraction. The entire palladium complexes went to liquid crystal phase when heated to their melting temperature (T m), and a threaded texture was observed. The melting point of all the complexes changes regularly with the increase of the end alkoxy group length and the flexible spacer unit in the ligand polymer. It is worth noting that some of the complexes without end substituent groups in the ligand polymer were also found to show liquid crystal behaviors, which would be a subject for further investigation. Copyright © 2001 John Wiley & Sons, Ltd.

Synthesis and characterization of a series of liquid crystal polymers with X-shaped two-dimensional mesogenic units

A series of liquid crystal polymers (LCPs) with X-shaped two-dimensional mesogenic units has synthesized via low temperature solution polycondensation. The liquid crystalline behaviors of the polymers were characterized using differential scanning calorimetry, polarized microscopy and X-ray diffraction. It was found that all the polymers show nematic thermotropic liquid crystalline characteristics, and their melting temperature Tm and isotropization temperature Ti change regularly with varying of the length of the flexible spacer and of the side groups © 1997 John Wiley & Sons, Ltd.

Synthesis and characterization of a series of liquid crystal polymers with X-shaped two‐dimensional mesogenic units

A series of liquid crystal polymers (LCPs) with X-shaped two-dimensional mesogenic units has synthesized via low temperature solution polycondensation. The liquid crystalline behaviors of the polymers were characterized using differential scanning calorimetry, polarized microscopy and X-ray diffraction. It was found that all the polymers show nematic thermotropic liquid crystalline characteristics, and their melting temperature Tm and isotropization temperature Ti change regularly with varying of the length of the flexible spacer and of the side groups © 1997 John Wiley & Sons, Ltd.

An X-Ray Diffraction Study of Liquid Crystal Polysiloxane Copolymers

Abstract The smectic and nematic phases of a series of liquid crystal polymers based on (I) a poly (hydrogenmethylsiloxane) backbone and (II) a poly (hydrogenmethyldimethylsiloxane) copolymer backbone have been investigated by x-ray diffraction.