Characterization Of Liquid Crystalline Poly Research Articles

Synthesis and characterization of liquid crystalline poly(ether-ketone)s containing 1-benzyl-4-piperidone moiety as a pendent group

A series of poly(ether-ketone)s (PEKs) having 1-benzy-4-piperidone moiety as a pendant group was successfully synthesized from 3,5-bis(3-ethoxy-4-hydroxybenzyldehyde)-1-benzyl-4-piperidone and various dibromoalkanes employing solution polycondensation method. The structures of the novel monomer, model compound, and PEKs were characterized using FT-IR, 1H NMR, and mass Spectroscopy. The thermal and liquid crystalline properties of the synthesized polymers were evaluated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The study revealed that all of the prepared polymers are thermally stable. The glass transition temperature, Tg, was in the range of 46–117 °C, and the temperature that caused a 5% weight loss was over 290 °C. DSC profiles of PEKs with aliphatic spacer lengths 4 and 8 revealed both melting transition, Tm, and isotropization transition, Ti, peaks. These results indicate that the polymers possess a thermotropic liquid crystal structure. An optical microscopy study called polarized optical microscopy (POM) confirmed that these polymers have features of liquid crystals. Threaded and droplet textures could be seen under POM.

Synthesis and characterization of liquid crystalline poly(N‐acylethyleneimine)s

AbstractThe synthesis of three cyclic imino ethers containing mesogenic groups attached to the heterocyclic unit through flexible spacers is described. Cationic ring‐opening isomerization polymerization of two of them, i.e., 2‐[4‐(4‐methoxy‐4′‐biphenyloxy)butyl]‐2‐oxazoline (MeOBiph‐4‐Oxz) and 2‐[6‐(4‐methoxy‐4′‐biphenyloxy)hexyl]‐2‐oxazoline (MeOBiPh‐6‐Oxz) provided thermotropic liquid crystalline (LC) poly(N‐acylethyleneimine)s, whereas the polymerization of 2‐[4‐(4‐phenylphenoxy)butyl]‐2‐oxazoline (BiPh‐4‐Oxz) led to a crystalline polymer.

Synthesis and characterization of liquid crystalline poly(p-vinylbenzyl ether)s

The synthesis and characterization of poly(p-vinylbenzyl ether)s containing 4-oxybiphenyl or 4-oxy-4′-methoxybiphenyl mesogens or a 4-oxy-4′-methoxybiphenyl mesogen which is connected to the benzyl ether group through one, two or three oligo(oxyethylene) units, are presented. The first two polymers exhibit a nematic mesophase while the last three a highly ordered smectic mesophase.

Structural isomerism in Polycondensates. Part IV. Synthesis and characterization of liquid crystalline poly(azomethines) and low molecular weight model compounds

AbstractWith the aim to investigate the influence of structural isomerism on the mesomorphic thermal stability in main chain thermotropic polycondensates, a series of poly(azomethines) and low molecular weight models have been prepared. The model compounds exhibit smectic and/or nematic mesophases whose stabilites are very sensitive to structural modifications. On the basis of the above results, monomers 2, 5, 6, 8, 9, 23, 25, and 26 were selected to synthesize oligomers 27–23. The oligomer 33 obtained from the nonsymmetric diamine 23 has a lower melting point than the symmetric oligomer 28, but a similar liquid crystalline range.

Polymerization and characterization of liquid crystalline poly(hexyl isocyanate)/styrene solutions

Le polyisocyanate est assez soluble dans le styrene et le chlorure de vinylidene pour former des cristaux liquides